Ambient Pressure X-ray Photoelectron Spectroscopy (APXPS): Present Status and Future Development at NSRRC

Ambient pressure X-ray photoelectron spectroscopy is considered one of the most exciting photoelectron spectroscopy techniques developed during the past two decades to address the electronic structure properties of the materials under in-situ and in-operando environments [1, 2]. Through the ingenious design of sample cells, the technique has been applied to investigate the heterogeneous reactions covering gassolid, liquid-solid, and gas-liquid interfaces routinely in a few mbar pressure range. This capability allows researchers to explore new research frontiers in areas such as catalysis, renewable energy, environmental chemistry, etc. [3–5]. The past decade has seen a greater proliferation of both lab-based and synchrotron-based APXPS instruments, propelled by the availability of commercial APXPS analyzers [6, 7].