Vacuum Ultraviolet Lamp Based Magnetic Field Enhanced Photoelectron Ionization and Single Photon Ionization Source for Online Time-of-Flight Mass Spectrometry
Vacuum Ultraviolet Lamp Based Magnetic Field Enhanced Photoelectron Ionization and Single Photon Ionization Source for Online Time-of-Flight Mass Spectrometry
复制标题
基于真空紫外灯的磁场增强光电子电离和单光子电离源用于在线飞行时间质谱分析
DOI：
10.1021/ac201791n
复制
发表时间：
2011-12-01
影响因子：
7.4
通讯作者：
Li, Haiyang
中科院分区：
文献类型：
--
作者：
Wu, Qinghao;Fua, Lei;Li, Haiyang
为正交加速飞行时间质谱仪 (oaTOFMS) 开发了与单光子电离 (SPI) 相结合的磁场增强光电子电离 (MEPEI) 源。使用商用射频（rf）供电的真空紫外（VUV）灯作为SPI光源，通过光电效应产生的光电子被加速以诱导电子电离（EI）。 MEPEI是通过用环形永磁体施加约800G的磁场而获得的。与非磁场光电子电离源相比，MEPEI中SO(2)、SF(6)、O(2)和N(2)的信号强度提高了2个数量级以上，光电子能量在20 eV左右，同时仍然保留了大部分软电离特性。 SIMION模拟表明MEPEI灵敏度的提高归因于电子移动路径的增加和电子传输的改善。在 4 秒的检测时间内，SO(2) 和苯的检测限分别为 750 和 80 ppbv。通过监测聚氯乙烯 (PVC) 热解产物和 SF(6) 气体杂质排放过程中的中间产物，证明了该源的优点，包括广泛的可电离化合物、减少的碎片以及低能 MEPEI 的良好灵敏度。
A magnetic field enhanced photoelectron ionization (MEPEI) source combined with single photon ionization (SPI) was developed for an orthogonal acceleration time-of-flight mass spectrometer (oaTOFMS). A commercial radio frequency (rf) powered vacuum ultraviolet (VUV) lamp was used as SPI light source, and the photoelectrons generated by photoelectric effect were accelerated to induce electron ionization (EI). The MEPEI was obtained by applying a magnetic field of about 800 G with a permanent annular magnet. Compared to a nonmagnetic field photoelectron ionization source, the signal intensities for SO(2), SF(6), O(2), and N(2) in MEPEI were improved more than 2 orders with the photoelectron energy around 20 eV, while most of the characteristics of soft ionization still remained. Simulation with SIMION showed that the sensitivity enhancement in MEPEI was ascribed to the increase of the electron moving path and the improvement of the electrons transmission. The limits of detection for SO(2) and benzene were 750 and 80 ppbv within a detection time of 4s, respectively. The advantages of the source, including broad range of ionizable compounds, reduced fragments, and good sensitivity with low energy MEPEI, were demonstrated by monitoring pyrolysis products of polyvinyl chloride (PVC) and the intermediate products in discharging of the SF(6) gas inpurity.