本综述探讨了电化学原位偏振调制红外反射吸收光谱（PM IRRAS）在电极表面薄膜结构、取向和构象研究中的应用。该技术基于红外光谱表面选律，利用p偏振光在金属表面的增强和s偏振光的衰减特性，通过两者的差谱消除溶剂背景吸收，从而获取单一电极电位下表面物种的红外吸收信息。相比之下，另外两种流行的原位红外光谱技术，差减归一化界面傅立叶变换红外光谱 (SNIFTIRS) 和表面增强红外吸收光谱 (SEIRAS)，需要进行电位差谱以消除本体溶液的信号。本文首先简要介绍了偏振调制红外反射吸收光谱的操作流程及消除背景吸收的方法，随后通过三个实例展示了该技术在仿生生物膜研究中的应用：束缚磷脂双层膜、大肠杆菌素在磷脂双层中的结构分析，以及金电极表面核脂单层膜的研究。最后，以氧化石墨烯在电化学还原过程中的结构变化为例，阐述了偏振调制红外反射吸收光谱在材料科学中的广阔应用前景。

This feature article illustrates the potential of polarization modulation infrared reflection absorption spectroscopy (PM IRRAS) to provide molecular-level information about the structure, orientation and conformation of constituents of thin films at electrode surfaces. PM IRRAS relies on the surface selection rules stating that the p-polarized IR beam is enhanced, while the s-polarized beam is attenuated at the metal surface. The difference between p- and s-polarized beams eliminates the background of the solvent and provides IR spectra at a single electrode potential. In contrast, two other popular in situ IR spectroscopic techniques, subtractively normalized interfacial Fourier transform infrared spectroscopy (SNIFTIRS) and surface-enhanced infrared absorption spectroscopy (SEIRAS), provide potential difference spectra to remove the signal from the bulk solution. In this feature article, we provide a brief tutorial on how to run the PM IRRAS experiment and describe the methods used for background elimination first. The application of the PM IRRAS in the biomimetic research is then illustrated by three examples: construction of a tethered bilayer, reconstitution of colicin into a phospholipid bilayer and determination of the orientation of nucleolipids in a monolayer assembled at a gold electrode surface. Finally, the structural changes of graphene oxide during its electrochemical reduction are described to highlight the promising application of PM IRRAS in materials science.