Mass spectrometry is an analysis technology that ionizes chemical substances and separates and records various ions according to their mass-to-charge ratio and abundance. It can provide qualitative and quantitative information and is one of the most commonly used methods in chemical analysis. As a versatile and sensitive universal analysis tool, mass spectrometry is widely used in life science, environmental science, food, medicine and other fields.

　　Ionization technology is a prerequisite for mass spectrometry analysis. Samples can only be detected by mass spectrometry after being ionized. Ionization technology can be divided into hard ionization and soft ionization. In the field of organic mass spectrometry, electron bombardment ionization (EI) is the only hard ionization technology and the earliest developed ionization technology. With the development of mass spectrometry technology, soft ionization technologies such as chemical ionization (CI), electrospray ionization (ESI), and matrix-assisted laser desorption ionization (MALDI) have emerged. Compared with hard ionization, soft ionization produces fewer fragment ions, which is suitable for samples that are easily broken or ionized, and has a great influence on the development of mass spectrometry.

　　Among them, single-photon ionization using vacuum ultraviolet (VUV) radiation has ionization ability including polar and non-polar substances without matrix effects, and therefore has great application potential. The ionization energy of most molecules and free radicals is around 10eV, which is located in the vacuum ultraviolet band of light. Vacuum ultraviolet photoionization mass spectrometry technology absorbs the energy of a single photon in the molecule and “soft” ionizes its ionization energy, which can avoid the generation of fragment ions and directly obtain the quality information of the parent ion. In the past ten years, the coupling of vacuum ultraviolet photoionization and mass spectrometry has attracted extensive attention and a lot of research.

Recently, the team of Zhang Weijun, Anhui Institute of Optics and Fine Mechanics, Institute of Material Science, Chinese Academy of Sciences, has made new achievements in vacuum ultraviolet photoionization mass spectrometry technology, and developed a small vacuum ultraviolet photoionization reflection time-of-flight mass spectrometer. Published online in the Journal of the Scientific Instrument Review of the American Physical Society.

　　The research team used vacuum ultraviolet discharge lamps as the ionization source to develop a cage-shaped photoionization source with ion focusing effect, which improves the detection sensitivity through the high efficiency collection of ions in the ionization zone. At the same time, the use of key technologies such as the vertical introduction structure and secondary space focusing enables the miniaturized mass spectrometer to have higher mass spectrometry resolution capabilities. The vacuum ultraviolet photoionization time-of-flight mass spectrometer has been well used in the study of atmospheric free radical reaction kinetics.

　　The advancement of mass spectrometry technology has great significance for my country's scientific research work. Especially in the case where most high-end mass spectrometry instruments are monopolized by foreign manufacturers, the breakthrough of independent mass spectrometry technology will open up a new situation for my country's scientific research.