表面离化源工作参数对离子迁移率谱的影响

Effect of Work Parameters for Surface Ionization Source on Ion Mobility Spectrum

根据表面离化过程中样品分子在离化材料表面直接离化的特点,设计了一种样品离化和离子注入一步完成的面-网结构表面离化源。以金属钼为离化材料,三乙胺为测试样品,研究了离化源温度、离子门开门脉冲宽度和高度对离子谱图的影响。结果表明,离子流信号强度随离化温度升高迅速增强但离化源寿命缩短,理想的离化温度约为400℃;增加开门脉冲宽度和高度有利于提高系统响应灵敏度,但会降低分辨率,合适的脉冲宽度和高度分别为100"s和500V。该离化源制作简单,性能稳定,工作寿命长,在优化的工作参数下三乙胺的检出限<0.04mg/m3。

There is no reactant ion in surface ionization and sample molecules are ionized at the emitter surface.Based on this feature,an ionization source was designed in a form of a plane（the emitter） parallel to a grid（the gate）.Molybdenum was used as the emitter material and triethylamine（TEA） as the test compound,the effect of the emitter temperature and the gate voltage pulse width and height on ion mobility spectrum have been investigated.The results indicate that the intensity of ion current is strongly dependant on the emitter temperature,the optimal temperature is about 400 ℃;the device sensitivity enhances as the gate voltage pulse width and height are increased,but the resolution lowered,the optimal pulse width and height are 100 μs and 500 V respectively.The ionization source is easy to be fabricated with high stablility and long working life.Under the optimized parameters,the detection limit of triethylamine is less than 0.04 mg/m3.