地质样品中铼、锇同位素比值的负离子质谱测量

The Measurement of the Isotopic Ratios of Rhenium and Osmium of Geological Samples by Negative Ionization Mass Spectrometry

摘要: 研究建立了Re－Os地质样品中铼、锇同位素比值的负离子热表面电离质谱测量方法。俄同位素的测量，采用六波俄酸高真空还原金属俄，双带覆盖硝酸钡助发射剂等涂样技术，较之不作还原，离子流增强两个数量级。主要同位素比值比测量精度优于0．04％。按照等概率模型对OsO3-离子测量比值作了氧同位素校正，其结果与Os+离子测量结果相一致。应用本方法测量了黄龙锦辉钼矿的Re－Os年龄，223．4±1．5Ma（2σ），与美国地调局的测量结果224O±20Ma（2σ）氧同位素校正基本一致。

Abstract: A new method of the measurement of the isotopic ratios of rhenium and osmium by negative ionization mass spectrometry (NTIMS)was developed. In the procedure of Os measurement,first H,Br,Os on the filament was reduced to Os metal in high vacuum, then the mixed solution of Ba (NO3)2 and NaOH was used as an emission auxiliary. Therefore, the lon current was increased to 2 magnitudes. The precision of the main ration was better than 0. 04%. The results of the experiments were corrected for oxygen isotopes according to the equi-probability model. The Re-Os age of Re-Os age reference HLP determined by this method was 223-4±1.5Ma.