Acquisition and Development of an Ultra Violet Laser Sulfur Isotope Microprobe for the Analysis 32S, 33S, 34S, and 36S in Sulfide Minerals

获得一台配备4个收集器和4通道输出的同步分析SF6离子束的新型同位素比监测气相色谱仪（IRMS-GC MS），将有可能开发一种新的紫外（UV）激光氟化微探针，用于分析硫化物矿物中的32S、33S、34S和36S。根据以往硅酸盐矿物中氧同位素原位微分析的成功经验，在d33S和d34S中，测量硫化物矿物上直径为50微米的斑点的精度应为0.1至0.2 / mil，在？33S中为0.05 / mil。由于同位素36S的稀有性，对d36S的分析精度将较低。一种新的紫外激光宏探针和气相色谱净化系统已经建立并验证了400微米直径的硫同位素点测量使用现有的质谱仪，不能进行气相色谱连续流操作。NSF-MRI要求新的IRMS-GC质谱仪将分析空间分辨率从400微米提高到50微米。新的硫同位素微探针将用于验证通过硫化物矿物直接氟化发现太古宙岩石中不依赖质量的硫同位素异常的有效性。提出的异常与地球大气氧合之间的关系将通过对跨越太古宙-元古代过渡的岩心的详细测量来检验。通过对矿物间分选和矿物内同位素非均质性的空间解析分析，将研究固定岩石中质量独立特征的机制。这种新型微探针分析微克样品的能力将用于微生物对硫同位素分馏的实验室研究。新型硫同位素微探针的使用将向整个研究界的合格用户开放。

0215953RumbleThe acquisition of a new isotope-ratio-monitoring, gas chromatograph inlet mass spectrometer (IRMS-GC MS) equipped with four collectors and four channel output for simultaneous analysis of the ion beams of SF6 will make it possible to develop a new ultraviolet (UV) laser fluorination microprobe for the analysis of 32S, 33S, 34S, and 36S in sulfide minerals. Based on previous experience with the successful in situ microanalysis of oxygen isotopes in silicate minerals, it should be possible to measure 50-micrometer diameter spots on sulfide minerals with a precision of 0.1 to 0.2 per mil in d33S and d34S and 0.05 per mil in ?33S. Analysis for d36S will be at a lower level of precision owing to the rarity of the isotope 36S. A new UV laser macroprobe and GC purification system has already been built and validated for 400 micrometer diameter spot measurements of sulfur isotopes using an existing mass spectrometer that is incapable of GC-continuous flow operation. The new IRMS-GC MS requested from NSF-MRI is needed to improve analytical spatial resolution from 400 to 50 micrometers. The new sulfur isotope microprobe will be used to test the validity of the discovery of mass-independent sulfur isotope anomalies in Archean rocks by direct fluorination of sulfide minerals. The proposed relationship between the anomalies and the oxygenation of Earth's atmosphere will be tested by detailed measurements of drill cores spanning the Archean-Proterozoic transition. The mechanisms responsible for fixing mass-independent signatures in rocks will be investigated through spatially resolved analyses of inter-mineral fractionations and intra-mineral isotopic heterogeneity. The new microprobe's capacity to analyze microgram samples will be put to use in a laboratory study of the fractionation of sulfur isotopes by microbes. Use of the new sulfur isotope microprobe will be open to qualified users from throughout the research community.