基于静态气体质谱仪的Xe稳定同位素高精度分析

Highly Accurate Measurements of Xenon Stable Isotope Abundance on Static Gas Mass Spectrometer

为解决氙(Xe)的九种稳定同位素质量差异大(约9.6%),质谱探测器接收难的问题,利用Helix MC Plus静态气体质谱仪,建立一种测量Xe全部稳定同位素丰度比的高精度质谱分析方法,快速、准确获得Xe的全部稳定同位素丰度。首先对混合气体样品中的Xe进行提取分离与纯化等条件实验,减小其他惰性气体及活性组分对Xe同位素分析测量的影响,再使用跳峰和多接收两种方式相结合的测量方法,实现在进样量极小时,基于Helix MC Plus型静态气体质谱仪的Xe全部稳定同位素的高精度测量,并利用天然丰度Xe标准气体对配制的混合气体样品测量结果进行线性校正。结果表明,在进样量约1.12×10^(-12)mol条件下,法拉第杯测量129 Xe/^(132)Xe、^(130)Xe/^(132)Xe、^(131)Xe/^(132)Xe、^(134)Xe/^(132)Xe、^(136)Xe/^(132)Xe丰度比的相对标准偏差≤0.24%,对于使用计数法测量124 Xe/^(132)Xe、126 Xe/^(132)Xe丰度比的相对标准偏差分别为0.22%和0.39%。本方法稳定性好、精度高,可以实现痕量Xe稳定同位素的丰度比质谱分析测试。

A high accuracy method for Xenon isotope abundance measurements was developed on a Helix MC Plus static gas mass spectrometer,in order to solve the problem that the mass difference of the nine stable isotopes of Xe is large(about 9.6%)and the mass spectrometry detector is difficult to accept,for get the abundance of all the stable isotopes of Xe quickly and accurately.The gas sample containing Xenon was purified and separated before introduced into the mass spectrometer analyzing chamber firstly,which helps reducing the influence on Xenon isotopic measurement brought by other noble gases and active components.Then,a measurement method combining peak hopping and multi reception was used to achieve high precision measurement of all stable isotopes of Xe at extremely small sample amount based on the Helix MC Plus static gas mass spectrometer.The measured data were corrected by referring to the Xenon isotopic reference gas finally.Results show that,under the condition of small sample amount(approximately 1.12×10^(-12)mol),the relative standard deviation(RSD)of the measured 129 Xe/^(132)Xe,^(130)Xe/^(132)Xe,^(131)Xe/^(132)Xe,^(134)Xe/^(132)Xe,^(136)Xe/^(132)Xe were within 0.24%by Faraday,and 124 Xe/^(132)Xe,126 Xe/^(132)Xe were within 0.22%and 0.39%by counting method separately.This method achieves abundance ratio analysis of trace Xe stable isotopes with good stability and high accuracy.