Optimization of SIMS analytical parameters for water content measurement of olivine
Optimization of SIMS analytical parameters for water content measurement of olivine
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DOI：
10.1002/sia.6729
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发表时间：
2019-12
影响因子：
1.7
通讯作者：
Zhang Wanfeng;X. Xia;Takahashi Eiichi;Li Li-Li;Q. Yang;Yanqiang Zhang;Ya-Nan Yang;Liu Mingliang;Chunkit Lai
中科院分区：
文献类型：
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作者：
Zhang Wanfeng;X. Xia;Takahashi Eiichi;Li Li-Li;Q. Yang;Yanqiang Zhang;Ya-Nan Yang;Liu Mingliang;Chunkit Lai
二次离子质谱法（SIMS）具有高精度、高灵敏度和直接原位微测量能力，在地球科学研究中有着广泛的应用。该技术在超高真空（UHV）条件下操作，特别是用于测量挥发性物质，如氢，或名义上无水矿物（NAMs）中的水含量。为了最小化水背景并获得NAMs（如橄榄石）中准确和精确的含水量，研究了CAMECA IMS 1280‐HR系统的关键参数，如预溅射时间、场孔径（FA）、动态传递开/关和主光束电流强度。当腔室真空度约为2 × 10−9 mbar时，我们将DTOS设置为OFF，光栅尺寸为50 μm，主光束电流为5 nA， FA为2000 μm，预溅射时间为170秒。因此，通过对圣卡洛斯橄榄石的分析，得出了大约1.2 ppmw的水背景和3.6 ppmw的检测限（LOD）。同时，对一系列橄榄石矿物的含水量和均匀性进行了表征，以期作为SIMS含水量测量的参考物质。通过将傅里叶变换红外（FTIR）结果与SIMS测量的16O1H−/16O−比值进行比较，建立了橄榄石含水量校准曲线。在本研究中，含水量测量的准确度和精密度估计优于约10%。
Secondary ion mass spectrometry (SIMS) has a wide range of applications in Earth Science research, thanks to its high precision and sensitivity, and its capacity in direct insitu micromeasurement. The technique is operated in ultra‐high vacuum (UHV) conditions, especially for the measurement of volatiles such as hydrogen, or the water content in nominally anhydrous minerals (NAMs). To minimize the water background and obtain accurate and precise water contents in NAMs (eg, olivine) critical parameters such as presputtering time, field aperture (FA), dynamic transfer on/off, and primary beam current intensity were investigated for a CAMECA IMS 1280‐HR system. When the chamber vacuum reaches approximately 2 × 10−9 mbar, we set the DTOS OFF, raster size to 50 μm and primary beam current to 5 nA, and used 2000 μm FA and 170‐second presputtering time. Consequently, an approximately 1.2 ppmw water background and 3.6 ppmw limit of detection (LOD) were yielded, from analyzing the San Carlos olivine. Meanwhile, the water content and homogeneity of a range of olivine minerals were characterized for potential use as reference materials for SIMS water content measurement. Olivine water content calibration curve was also established by comparing the Fourier transform infrared (FTIR) results with the SIMS‐measured 16O1H−/16O− ratios. Accuracy and precision of water content measurement were estimated to be better than approximately 10% in this study.