新型单光子电离和光电子电离复合电离源的研究及应用

摘要

The characters and applications of combined single photon ionization (SPI) and photoelec-tron ionization (PEI) source were introduced. The ion source can generate dominated molecular ions in SPI mode and fragments ions same as standard El spectrum in PEI mode. The switch time between the two modes was several microseconds. The limit of detection in SPI mode was reduced by increasing the optical path in the ion source. Achieved detection limits were 0. 05 mL/m3 and 20 mL/m3 for benzene in SPI mode and SO2 in PEI mode with accumulating time of 4 s respectively. Products in the process for catalytic dehydrogenation of alkanes were monitored in SPI mode. In addition, the samples of SF6 were analyzed in PEI mode with low energy electrons and the impurities were identified.%复合电离源在单光子电离模式下可以产生分子离子信号,易于确定分子量；在光电子电离模式下,70 eV电子能量可以产生含有物质结构信息的碎片峰,实现物质的结构鉴定.两种电离模式可以实现毫秒级迅速切换.本研究通过提高光程降低了单光子电离模式下的检出限.在单光子电离模式下,对苯的检出限为50 μg/m3(累加时间为4s)；光电子电离模式下,对SO2的检出限为20 μL/m3(累加时间4 s).利用复合电离源的单光子电离模式分析了烷烃催化脱氢产物,成功实现了碳链长度为8～12的烷烃,烯烃和二烯烃的在线分析和监测.此外,还利用低能电子的光电子电离模式分析了高压变压器保护气,检测了主要杂质成分,为高压变压器中故障的快速诊断提供依据.