40Ar/39Ar定年自动去气系统的研制及其性能  

An automatic degassing system for 40Ar/39Ar dating

作　　者：张万峰[1,3] 邱华宁 郑德文 蒋映德 白秀娟[2] ZHANG Wan-feng;QIU Hua-ning;ZHENG De-wen;JIANG Ying-de;BAI Xiu-juan(State Key Laboratory of Isotope Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China;Key Laboratory of Tectonics and Petroleum Resource,Ministry of Education,China University of Geosciences,Wuhan 430074,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院广州地球化学研究所同位素地球化学国家重点实验室,广东广州510640 [2]中国地质大学(武汉)资源学院构造与油气教育部重点实验室,湖北武汉430074 [3]中国科学院大学,北京100049

出　　处：《地球化学》2020年第5期509-515,共7页Geochimica

基　　金：中国科学院广州地球化学研究所仪器功能开发项目(GIG-GNKF-201801);国家自然科学基金(41603045)。

摘　　要：稀有气体质谱仪的系统本底是稀有气体同位素测试结果的重要评价参数。本次研究简要介绍了1套自主研发的自动化40Ar/39Ar定年与稀有气体同位素测定的外部设备。应用上位机与可编程控制器作为控制单元,以继电器、热电偶等为执行器,设计了1套适用于稀有气体质谱仪的自动化控制及控温系统,可实现实时数据的获取并具备比例-积分-微分闭环控制等功能。通过上位机可实时对相应部件的升温速率和目标温度进行控制,并对样品腔、冷阱、纯化泵、离子泵及管道分别设计出个性化的烘烤去气方案。整个系统运行稳定,将繁杂、费时的烘烤过程自动化,以确保仪器系统的安全,恒温时温度变化小于±2℃。烘烤后,整套40Ar/39Ar定年装置(ARGUSⅥ质谱仪、纯化系统和2个样品盘)的整体上升率低至6.98×10−13 mL/min,获得了稳定的空气40Ar/36Ar比值(298.55±0.03,1σ,MSWD=1.18,n=300)和理想的ZBH-25坪年龄,充分展现了该系统的优越性能。Determining the background of the noble gas mass spectrometer is highly important for the analysis of Ar isotopes.An inhouse automatic degassing system was therefore developed,according to actual analytical requirements.It encompasses a computer,a programmable logic controller,an analog/digit module,relays,heaters,and thermoelements.All devices can be controlled using self-programming software.This design can degas all parts of the equipment,including the sample chamber,cold trap,gatter,ion pump,and stainless steel pipeline.PID control is used in the degassing system to degas more individually and enhance safety.Moreover,the complex baking process has been simplified and can easily be upgraded for other equipment.Our results show that the variation in the constant degassing temperature is<2℃,and the static rate of rise in the whole system(including two sample chambers)is<6.98×10−13 mL/min,after systematic backing with the automatic degassing system.Using 300 air Ar analyses,we obtained consistent atmospheric 40Ar/36Ar ratios with a weighted mean of(298.55±0.03,1σ,MSWD=1.18,n=300),and an excellent plateau age for the ZBH-25 biotite standard.This indicates that the proposed system is highly stable and reliable.

关 键 词：稀有气体质谱 自动化控制 烘烤 去气 

分 类 号：P597[天文地球—地球化学] P599[天文地球—地质学]