痕量氪同位素的分离方法与高精度质谱测量  

Separation Method and High Accuracy Mass Spectrometry Measurement of Trace Krypton Isotope

作　　者：李萌 关业栋 李志明[1] 韦冠一[1] 方随 汪伟 李雪松[1] 徐江[1] LI Meng;GUAN Yedong;LI Zhiming;WEI Guanyi;FANG Sui;WANG Wei;LI Xuesong;XU Jiang(Northwest Institute of Nuclear Technology,Xi’an 710024,China)

机构地区：[1]西北核技术研究所,西安710024

出　　处：《现代应用物理》2024年第6期122-129,共8页Modern Applied Physics

基　　金：国家重点研发计划资助项目(2021YFF0700100)。

摘　　要：氪(Kr)同位素的组成可以提供关于地球大气演化、地下水年龄、冰芯记录及核环境监测等方面的关键信息。为解决Kr同位素测量所面临的基体复杂、本底难控制、样品需求量大和难以实现稳定同位素全谱分析等难题,利用自主搭建的惰性气体分离纯化制冷平台,建立Kr-Xe, Kr-Ar分离方法的低温吸附纯化及分离技术,并基于静态气体质谱仪,通过跳峰法实现所有同位素比值的测量;采用外标标准化法校正质量分馏效应,建立了一种Kr全部稳定同位素的高精度分析方法。结果表明,利用深冷不锈钢冷阱循环分离纯化法可使Kr-Xe和Kr-Ar分离度分别达到34和490,Kr的回收率约70%;在进样量约2.6×10^(-12)mol条件下,利用法拉第杯测量80Kr/84Kr,82Kr/84Kr,83Kr/84Kr,86Kr/84Kr的相对标准偏差小于等于0.13%,利用计数法测量78Kr/84Kr的相对标准偏差为0.16%,测量结果与参考值在不确定度范围内一致,证明该方法可快速、高精密度地实现超痕量Kr全部稳定同位素的准确测量。The composition of krypton(Kr)isotopes can provide critical information on various aspects such as the evolution of earth’s atmosphere,the age of groundwater,the ice core records,and the monitoring of the nuclear environment.To takle the problems of Kr isotope measurement,such as complex matrices,the background is difficult to control,large sample demand,and difficulty in achieving stable isotope full-spectrum analysis,a low-temperature adsorption purification and separation technology for Kr Xe and Kr Ar is established by using the self-built inert gas separation and purification refrigeration platform.Based on the static gas mass spectrometer,all isotope ratios are measured by the peak hopping method,and the mass fractionation effect is corrected by the external standard method,thereby a high-precision analysis method for all stable isotopes of Kr is established.The results show that the separation degree of Kr Xe and Kr Ar can reach 34 and 490,respectively.The recovery rate of Kr is about 70%by the deep cold stainless steel cold trap cyclic separation and purification method.The relative standard deviation of 80 Kr/84 Kr,82 Kr/84 Kr,83 Kr/84 Kr,and 86 Kr/84 Kr are measured by Faraday cup is≤0.13%,and the relative standard deviation of 78 Kr/84 Kr are measured by counting method is 0.16%under the sample injection amount of approximately 2.6×10^(-12) mol.The measurement results are consistent with reference values within the uncertainty range,demonstrating that this method can achieve all stable isotopes of ultra-trace Kr quickly and accurately.

关 键 词：Kr同位素 质谱 不锈钢冷阱 分离纯化 

分 类 号：TL99[核科学技术—核技术及应用] O657[理学—分析化学]