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还原态硫化物是大气主要污染物之一。本研究利用自行研制的磁增强光电子电离便携式飞行时间质谱,对还原态硫化物的测量方法进行了研究。光电子由真空紫外灯发射的10.6 e V的光子照射金属电极表面产生,通过调节引出电压控制光电子能量发生光电子电离。为提高光电子电离的效率,在电离区中设置了环形磁铁。利用SIMION软件模拟发现磁场的引入使电子呈螺旋运动,增加电子运动路径,同时实现电子向电离区中心的汇聚。实验结果表明,磁场的引入使3种还原态硫化物H2S,SO2和CS2的灵敏度分别提高了5.3、9.4和6.9倍,50 s检测时间对3种物质的检测限分别达到0.14、0.52和0.31 mg/m3(S/N=3)。结果表明,磁增强光电子电离的便携式飞行时间质谱仪有望应用于挥发性硫化物的源排放在线监测。
Reduced sulfide is one of the major pollutants in the atmosphere. In this study, the magnetically enhanced photoelectron ionization portable time-of-flight mass spectrometry developed by ourselves was used to study the measurement of reduced sulfide. Photoelectrons emitted by the vacuum ultraviolet lamp 10.6 e V photons generated on the surface of the metal electrode, by controlling the induced voltage to control the photoelectron energy occurs photoelectron ionization. To improve the efficiency of photoelectron ionization, a ring magnet is provided in the ionization zone. SIMION software was used to simulate the introduction of a magnetic field to make the electrons move in a spiral motion and increase the path of electron movement. At the same time, the convergence of electrons to the center of the ionization region was realized. The experimental results show that the sensitivity of three kinds of reduced sulfides, H2S, SO2 and CS2, are respectively increased by 5.3, 9.4 and 6.9 times by the introduction of magnetic field. The detection limits of the three substances at 50 s are 0.14, 0.52 and 0.31 mg / m3 (S / N = 3). The results show that magnetically enhanced photoelectron ionization portable time of flight mass spectrometry is expected to be applied to online monitoring of source emission of volatile sulfides.