Developement of Tandem, Double-focusing, Electron Impact, Gas Source Mass Spectrometer for Measurement of Isotopologues in Geochemistry

本仪器研制项目将设计和建造串联式、双聚焦、高分辨率、高灵敏度、电子碰撞、气体源、质谱仪。该仪器的目的是分析火山柱、地热温泉、碳氢化合物储藏库、地壳深层微生物群落、天然气水合物、土壤和地球大气中出现的稀有的双取代同位素。拟用该仪器研究的气体清单包括氮气(15N15N)、氧气(17O18O、18O18O)、CH4、N2O、SO2和OCS，但不限于这些气体。通过研究天然样品中的块状同位素同位素分布，可以从单相的测量中获得有关气体物种合成温度的信息。伴随合成反应的动力学同位素分馏效应可能提供关于特定反应机制盛行的数据。将需要一个广泛的实验校准计划，以评估使用新仪器的块状同位素的地质测温潜力和动力学同位素效应。使用拟议工具的预期结果是加深对当今大气层-水圈-岩石圈相互作用的了解。改进后的现代世界知识将被用来对地质记录中的古代大气代用品进行校准解释。最终目标是以极地冰芯或岩层等现有样本所允许的最大时间分辨率来了解地球大气的化学演化。一种性能空前的新型质谱计的使用可能会带来无法预测的应用。在对人类社会产生更广泛影响的背景下，对CH4和N2O等微量温室气体的研究将有助于评估全球变暖和气候变化。

This instrument development project will design and build a tandem, double-focusing, high-resolution, high-sensitivity, electron impact, gas source, mass spectrometer. The purpose of the instrument is to analyze rare, doubly-substituted isotopologues of gases occurring in volcanic plumes, geothermal hot springs, hydrocarbon reservoirs, deep crustal microbial communities, gas hydrates, soils, and Earth's atmosphere. The list of gases to be investigated with the proposed instrument includes N2 (15N15N), O2 (17O18O, 18O18O), CH4, N2O, SO2, and OCS but is not limited to them exclusively. The investigation of clumped isotope isotopologue distributions in naturally occurring samples confers the advantage of deriving information on temperature of synthesis of gas species from the measurement of a single phase. It is possible that kinetic isotope fractionation effects accompanying synthesis reactions may provide data on the prevalence of specific reaction mechanisms. An extensive program of experimental calibration will be required to assess both the geothermometric potential and kinetic isotope effects of clumped isotopologues with the new instrument. The expected outcome of use of the proposed instrument is to acquire a deeper understanding of present-day atmosphere-hydrosphere-lithosphere interactions. The improved knowledge of the modern world will then be used to develop calibrated interpretations of ancient atmospheric proxies in the geologic record. The ultimate goal is to understand the chemical evolution of Earth's atmosphere with as great a time resolution as permitted by available samples such as polar ice cores or rock strata. The use of a new mass spectrometer of unprecedented capability is likely to give rise to applications that cannot be predicted. In the context of broader impact on human society, the study of trace greenhouse gases such as CH4 and N2O will contribute to evaluating global warming and climate change.