质谱计样品增量法扣本底技术研究

The Residual Gas Background Calculation of Mass Spectrometer by Sample Quantity Increment

质谱计在分析样品气体时，常采用峰高相减法来扣除本底残气的干扰，该法不十分准确，特别是作痕量杂质分析时会引起很大误差；本文提出一种新的扣除法，称作样品增量法。改变样品进样量，然后根据各成分对应离子流的增量，计算出它们的相对浓度。由于本底残气的离子流增量为零，故而消除了残气的干扰。论文首次报导了封闭离子源独有的样品气流的喷口效应，造成了电离室内本底残气压强低于质谱室中值，采用本底残气抑制系数解出了样品杂质的真实值。

In the mass spectrometer analysis,it is used to eliminate the residual gas backgroundinterference by the difference of peakheight between the sample and background spectrum.Thismethod is not always exact,it takes bigger error especially at analysing trace gas,In this paper,a new elimination is reported,we name it the sample quantity increment.By means of a change of inlet sample quantity,we can measure ion current increment of each peak in the two spectra and then calculate their relative concentration. Because the increment of background is zero,its interference is eliminated,Jet effect of sample gas in the enclosed ion source is first explained and measured,it makes background pressure is ionization chamber lower than in mass spectrometerspace.In order to calculate true background ion current from the sample spectrum, a restraincoefficient is introduced.