Binding energy (B_E) referencing is critical to the reliability of chemical analysis performed by X-ray photoelectron spectroscopy. Although the procedure is straightforward for metallic samples, no universal solution is available for insulators, wherein a build-up of positive charge during photoemission results in an uncontrolled change in the B_E of the core-level peaks. As these peaks are used to assess the chemical bonding, shifts caused by charging lead to problems with spectra interpretation and contribute to an unacceptably large spread in the B_E values reported for the same chemical state. It is often unclear which referencing methods should be applied to which sample type and which referencing approaches should be rejected. In this Perspective, we review essential concepts and key experiments related to B_E referencing. We discuss energy diagrams and appropriate reference levels for conducting and insulating samples with and without electrical contact with the spectrometer, and we define criteria for the ultimate charge-reference method, using them to evaluate common referencing techniques. Although no method is free of issues, the most popular one, based on the adventitious carbon (AdC), turns out to be the least reliable. In particular, because the vacuum level aligns at the AdC–sample interface, the B_E of the reference C 1s peak from AdC is not constant but varies with the sample work function. To rectify the situation, we suggest easy-to-do control experiments that refute the notion that the C 1s peak has constant B_E. We further use the framework of energy diagrams to explain the consequences of the vacuum level alignment at the AdC–sample interface for measurements performed in the most common experimental configurations. Finally, we suggest ideas for improving the reliability of chemical analysis to stimulate the development of new referencing standards.

结合能 （BE_{） 参考}对于 X 射线光电子能谱进行的化学分析的可靠性至关重要。尽管该过程对于金属样品来说很简单，但没有适用于绝缘体的通用解决方案，其中光发射过程中正电荷的积累会导致核心能级峰的 B_E 不受控制地变化。由于这些峰用于评估化学键合，因此电荷引起的偏移会导致光谱解析问题，并导致相同化学状态下报告的 B_E 值出现不可接受的大扩散。通常不清楚哪些参考方法应该应用于哪种样品类型，以及应该拒绝哪些参考方法。在这个视角中，我们回顾了与 B_E 引用相关的基本概念和关键实验。我们讨论了在与光谱仪接触和不与光谱仪电接触的情况下导电和绝缘样品的能量图和适当的参考水平，并定义了最终电荷参考方法的标准，使用它们来评估常见的参考技术。尽管没有一种方法是没有问题的，但最流行的基于不定碳 （AdC） 的方法被证明是最不可靠的。特别是，由于真空度在 AdC-样品界面处对齐，因此 AdC 的参比 C 1s 峰的 B_E 不是恒定的，而是随样品功函数的变化而变化。为了纠正这种情况，我们建议进行易于进行的控制实验，以反驳 C 1s 峰具有常数 B_E 的观点。 我们进一步使用能量图框架来解释在最常见的实验配置中进行的测量在 AdC-样品界面处进行真空度对准的影响。最后，我们提出了提高化学分析可靠性的想法，以刺激新参考标准的开发。