Measurement on He and Ar Isotopic Compositions in Solid Samples by Mass Spectrometry
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摘要: 在现有设备的基础上，经多年实验，以空气Ｈｅ、Ａｒ同位素作标准样，采用同位素峰高比分析方法，在国内首次建立了一次进样完成固体样品中Ｈｅ、Ａｒ同位素的测量技术。文中就该项技术的要点，包括样品的前期处理、空气标准样的使用、仪器空白与灵敏度的测定、固体样品进样量的估算方法、测量条件等予以说明与分析。对应用该项技术获取的固体样品中Ｈｅ、Ａｒ同位素首批数据及其偏差，文中也进行了讨论。该项技术方法的建立，将为与惰性气体同位素相关的研究领域提供新的实验技术支撑，推动相关领域基础研究的开展和水平的提高。Abstract: An analytical technique for the simultaneous determination of He and Ar contents and isotopic tom-positions in rocks by static mass spectrometer has heen developed. The gases in rocks are extracted bymelting at 1 600℃.The purification of noble gases、an be made out by。titanium sponge Better at600℃，two Zr-Al Betters, and a Ti subliming Better. Heavier noble gases, such as argon, krypton andxenon are absorbed in a charcoal trap held at liquid nitrogen temperature. The purified helium and neonfractions are admitted to the mass spectrometer for helium measurement. After that, pumping out the Heand Ne, the charcoal trap is heated, and then the released(Ar+ Kr+ Xe)fractionis admitted to the massspectrometer for argon measurement. The air with constant isotopic compositions of noble gases is con-sidered as a standard sample. The average sensitivities of4He，20Ne and 36 Ar are(9. 00 +0.35）×10-10，(1. 4 01+0. 03 2）×10 -9 and(1. 76+0. 21）×10-10 cm3 STP,respectively. The blank levels of the sys-tem fo r4He and 36Ar are 1. 3860 ×109 and 4. 08×10-11cm3STP, respectively. Measured He and Ar con-tents and isotopic compositionsinedogites are given in this paper. Itis the first report on He and Arisotopic compositions in rocks in China.
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Key words:
- rock sample /
- He Ariso to pes /
- measurement of mass spectrometer
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