Photoelectron yield spectroscopy (PYS) is a widely used characterization method for studying the electronic structure of material surfaces, and photoelectron yield spectroscopy in air (PYSA) is one of its important development directions. PYSA is based on the photoelectric effect and obtains the threshold energy by measuring the photoelectron yield. It is divided into nitrogen-purged and separation types. The core components such as light source, monochromator, detector and photomultiplier tube are constantly being optimized. It has been developed by brands such as RIKEN, BUNKOUKEIKI and Yixing Sunnytech. Breakthroughs have also been achieved in laboratory research, and the application scope of PYSA is constantly expanding. Finally, this article looks forward to future development directions, including high-brightness deep-UV source, hybrid detector, and differential pumping system. These advances are expected to promote the transformation of PYSA from laboratory research to a wider range of applications in materials science and device engineering.

PYS,surface analysis,photoelectron emission yield spectroscopy in air,PYSA