Acquisition of a Dedicated Mass Spectrometer for TerrestrialNeon and Nitrogen Isotopic Studies

请拨经费购买一台将安装在斯克里普斯海洋研究所的质谱仪。该光谱仪将专门用于分析Ne和N的同位素，这些挥发性物质在玄武岩、地幔包体、钻石、海水、平流层空气和极地冰芯中的同位素特征对解释地球地幔的地球化学史以及地壳、海洋和大气的演化具有重要意义。拟议的质谱仪使用了一种在其收集器上切换离子束的新系统，以实现对质量20、21和22(霓虹灯)或28、29和30(氮)质量的基本上同时三次收集，从而使分析含有低浓度这些同位素的非常小的样品成为可能。

Funding is requested to acquire a mass spectrometer to be installed at the Scripps Institution of Oceanography. The spectrometer is to be dedicated to the analysis of the isotopes of neon and nitrogen, volatile species whose isotopic signatures in basalts, mantle-derived xenoliths, diamonds, ocean waters, stratospheric air, and polar ice cores are significant in the interpretation of the geochemical history of the Earth's mantle and the evolution of the crust, oceans and atmosphere. The proposed mass spectrometer uses a novel system of switching ion beams on its collectors to achieve essentially simultaneous triple collection for either masses 20, 21 and 22 (neon) or 28, 29 and 30 (nitrogen) to make possible the analysis of very small samples containing low concentrations of these isotopes.