基盤セッション
- 第1日 5月15日（月） 10:18～10:36 B会場（会議室1202）
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1B-O-1018 PDF
中性子照射と希ガス質量分析を用いた地質標準試料中の微量ハロゲンの定量
Halogens are among the most powerful tracers of volatile cycling in the Earth and planetary sciences. However, few analytical techniques can determine trace amounts of halogens, particularly Br and I in mantle-derived samples. The neutron irradiation noble gas mass spectrometry (NI-NGMS) is capable of measuring very low concentrations of halogens (<1 ppb) in very small samples (<1 mg). We report halogen concentrations determined for geological reference materials and their original blocks using NI-NGMS.
The halogen concentrations are systematically lower than the reference values for halogen-poor samples, probably resulting from contamination on the sample surface while preparing these reference materials. This is because the contaminated component was removed during sample preparation and/or preheating in a vacuum after sample loading into the analysis system.
We also propose an F-determination method using NI-NGMS based on Ne systematics. The F concentrations are consistent with their reference values within the uncertainty or slightly lower than the reference F concentrations. Some Ne might diffuse from the fine-powdered samples. Alternatively, surface contamination observed in Cl, Br, and I may explain the lower concentrations than the reference values.