[ Instrument R & D of Instrument Network ] Recently, the research team of Zhang Weijun of Anguang Institute has made new progress in the development of vacuum ultraviolet photoionization time-of-flight mass spectrometer. "The title was published online in the journal" Review of Scientific Instruments "of the American Physical Society (Rev. Sci. Instrum. 91, 043201, 2020).
Figure 1 Ion trajectory and structure of a small vacuum ultraviolet photoionization reflection time-of-flight mass spectrometer
Figure 2. (a) Cage-focused electric field and (b) Simulation of ion flight trajectories in parallel electric field
For most molecules and free radicals, their ionization energy is around 10 eV, which is located in the vacuum ultraviolet band of light. Vacuum ultraviolet photoionization mass spectrometry technology absorbs single photon energy by molecules to "soft" ionize near its ionization energy, which can avoid the generation of fragment ions and directly obtain the quality information of the parent ions. It is especially suitable for reactions in complex reaction systems such as atmospheric chemistry and combustion. Real-time online detection of substances, products and chemically active reaction intermediates (such as free radicals).
The team's associate researcher Tang Xiaofeng and Dr. Wen Zuoying, etc., designed and developed a small vacuum ultraviolet photoionization reflection time-of-flight mass spectrometer using vacuum ultraviolet discharge lamp as the ionization source, and applied it to atmospheric free radical reaction kinetics the study. By designing a new focused electric field with a cage structure, high-efficiency collection of ions in the ionization zone is achieved, and the detection sensitivity of the mass spectrometer is improved (free radical sensitivity reaches 0.3 ppb). At the same time, by adopting key technologies such as vertical introduction structure and secondary space focusing, the high mass spectrometry resolution capability of miniaturized mass spectrometer (M / â–³ M = 2000, FWHM) is realized.
This research work was supported by funding from the National Natural Science Foundation of China, the National Key R & D Program, and the Chinese Academy of Sciences International Cooperation Priority Program.
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