Collaborative Research: Improvements in the Application of the Mossbauer Effect to Studies of Minerals

提出了一套Moessbauer光谱实验，旨在实现矿物中Fe3+和Fe2+含量的真正定量。将确定与峰面积与物种丰度相关的价态和地点特定的无反冲分数“校正”因子，将在一组岩石学上重要的矿物上测试四种商业可用的Moessbauer数据处理软件包，并通过一组为期三年、两年的学生项目来突出现代仪器和建模的能力，旨在展示新技术的能力。本项目的智力价值有四个方面：(1)改进了对各种矿物的Moessbauer分析；(2)了解了所有类地行星上常见的造岩矿物辉石中的铁分布；(3)首次分析了长石中铁的氧化还原状态；(4)在必要的、良好约束的岩石学框架内研究了一种重要的变质矿物绿泥石。这项研究的更广泛的影响将是在解释矿物研究的穆斯堡尔光谱结果方面的全球改进。未来使用Moessbauer光谱研究矿物中铁的误差条将有效减少，并且将证明该技术具有新的能力，可以用于研究地质材料，即使是在微小样品或铁含量低的样品中。该项目将对6名女本科生（每年2名）产生很大的教育影响，她们将把这些项目作为毕业论文的主题。

A set of Moessbauer spectroscopy experiments are proposed, designed to enable true quantification of Fe3+ and Fe2+ contents in minerals. Valence state- and site-specific recoil-free fraction "correction" factors for relating peak areas to species abundance will be determined, four commercially-available software packages for processing of Moessbauer data will be tested on a set of petrologically-important minerals, and the capabilities of modern instrumentation and modeling will be highlighted through a set of three, two-year student projects designed to demonstrate the abilities of the new technique. The intellectual merit of this project of this project has four aspects: (1) improvement of Moessbauer analyses of wide range of minerals, (2) understanding iron distribution in pyroxene, which is a common rock-forming mineral on all terrestrial planets, (3) enabling for the first time analyses of the redox state of iron in feldspars, and (4) study of an important metamorphic mineral, chlorite, within the necessary, well-constrained petrologic framework. The broader impact of this research will be worldwide improvements in interpreting Moessbauer spectroscopic results from mineralogical studies. The error bars on future studies of iron in minerals using Moessbauer spectroscopy will be effectively reduced, and it will be demonstrated that this technique has new capabilities that can be used to study geologic materials even in tiny samples or those with a low percentage of iron. This project will have great educational impact on the six women undergraduates (two each year) who will make these projects the topics of senior theses.