MRI: Acquisition of a 213 nm Laser to Accompany an Existing Quadrupole ICPMS at Middlebury College

该合同将允许获得一台213 nm激光器，该激光器将与米德尔伯里学院现有的电感耦合等离子体质谱仪(ICPMS)相耦合，以实现激光烧蚀质谱仪(LA-ICPMS)。LA-ICPMS是一个快速发展的领域，它具有变革性，因为它允许快速分析矿物、贝壳和文物等材料上的非常小的区域(~10微米)。在米德尔伯里学院，LA-ICPMS将安装在地质系，主要用于进行铀(U)-铅(铅)测年和矿物的微量元素分析，这是过去构造的主要记录器。我们还预计生物学家和考古学家对了解古代工具的来源、材料和贸易模式感兴趣。这项提议得到了附近大学教职员工的广泛支持，将主要致力于本科生的研究，为学生提供实践研究体验，无论他们的项目范围或预算如何。用户将包括各种各样的学生，包括许多代表性不足的群体和第一次上大学的学生。获得激光将使许多项目能够以更有效率和更有效的方式进行。例如，激光烧蚀从根本上扩展了ICPMS可能的应用数量，包括以高空间分辨率原位分析材料的能力，这对许多应用是必不可少的。与溶液化学相比，它还减少了样品准备时间和复杂性，为现有的ICPMS提供了更广泛的用户基础。一个内部项目将利用近海沉积物岩心中碎屑矿物的来源来测试美国东部动态抬升的预测。另一个项目将利用古生代变质沉积岩中的碎屑锆石来测试阿巴拉契亚构造的长期模型。第三个内部项目将使用激光来更好地了解具有不安全阿尔法活动的基岩含水层中U和Th的来源。外部用户也提出了一系列项目想法。许多用户对U-Pb年代学感兴趣，以便测定火成岩的年龄，确定区域变质事件的时间，并利用碎屑锆石重建克拉通演化。其他用户对测量微量元素感兴趣，以确定考古文物的来源，了解年轻岩浆中心的岩石成因，并进行微量元素热压计。

This award will permit the acquisition of a 213 nm laser, which will be coupled to an existing inductively coupled plasma mass spectrometer (ICPMS) to enable laser ablation mass spectrometry (LA-ICPMS) at Middlebury College. LA-ICPMS is a rapidly growing field which has been transformative because it allows rapid analysis of very small regions (~10 microns) on materials such as minerals, shells, and artifacts. At Middlebury College, the LA-ICPMS will be housed in the Geology Department and will be used primarily to undertake uranium (U) - lead (Pb) dating and trace element analyses of minerals, which are the primary recorder of past tectonics. We also anticipate usage by biologists and by archaeologists who are interested in understanding the source materials and trade patterns of ancient tools. The proposal was widely supported by faculty at nearby colleges and will be primarily dedicated to undergraduate research, providing hands-on research experience for students regardless of the scope or budget of their project. Users will include a diversity of students, including many underrepresented groups and first time college students.Acquiring a laser will allow numerous projects to be undertaken in more efficient and effective ways. For example, laser ablation radically expands the number of possible ICPMS applications, including the ability to analyze materials in-situ with high spatial resolution, which is essential for many applications. It also reduces sample preparation time and complexity relative to solution chemistry, facilitating a wider user base for the existing ICPMS. One internal project will use the provenance of detrital minerals in offshore sediment cores to test predictions of dynamic uplift in the eastern U.S. Another will use detrital zircons in Paleozoic meta-sedimentary rocks to test longstanding models of Appalachian tectonics. A third internal project will use the laser to better understand the origin of U and Th in bedrock aquifers with unsafe alpha activity. External users have also put forward a range of project ideas. Many users are interested in U-Pb geochronology to date igneous rocks, establish the timing of regional metamorphic events, and reconstruct cratonic evolution using detrital zircons. Other users are interested in measuring trace elements to establish the provenance of archaeological artifacts, understand petrogenesis of young magmatic centers, and undertake trace element thermo-barometry.