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

要求拨款购买一台质谱仪，安装在斯克里普斯海洋学研究所。该光谱仪将专门用于分析氖和氮的同位素，这些挥发性物质在玄武岩、地幔源捕虏体、钻石、海水、平流层空气和极地冰芯中的同位素特征，对解释地幔的地球化学历史以及地壳、海洋和大气的演化具有重要意义。所提出的质谱仪使用一种新颖的系统，在其收集器上切换离子束，以实现质量20、21和22（氖）或28、29和30（氮）的基本同时三重收集，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.