RUI: Evaluating the Limits and Capabilities of Plasma Chemical Oxidation for Accelerator Mass Spectrometry

了解古代文物的年代有助于考古学家更好地将人类活动置于绝对的时间框架中。放射性碳定年法是20世纪以来考古学最重要的发展之一，它使直接测定过去材料的年代成为可能。然而，许多人工制品太小或太脆弱，无法用标准方法制备放射性碳定年样品。东密歇根大学的露丝·安·阿米蒂奇博士和她的考古学家和学生合作团队将评估等离子体化学氧化（PCO）的使用，以制备小型，碎片或易碎的人工制品样品，并通过加速器质谱法（AMS）进行放射性碳测年。该项目的重点是对濒危的岩石艺术、烧焦的骨头和易碎的纺织品碎片进行年代测定，否则这些碎片很难或不可能直接进行放射性碳测定。几十年来，PCO一直被用作从无机碳基质中提取有机碳的方法，以确定岩画的年代。这也是一种在不破坏脆弱有机材料的情况下测定其年代的方法，允许对同一样品进行重复测定。然而，关于PCO技术的能力和局限性，仍有许多有待了解的地方。PCO方法的验证对于以有意义的方式应用它来回答有关工件年龄的问题至关重要，否则这些问题可能会被忽视。阿米蒂奇小组长期以来一直在化学家和考古学家之间进行合作，通过放射性碳定年法和对文物的化学分析，更好地了解过去的人类社会和行为。该项目将开发一种方法来处理、处理和放射性碳定年的考古样本，否则无法定年，增加对人类和他们过去活动的了解。该奖项支持一个以本科生为主的大学（PUI）的不同科学家和学生群体与考古学家合作，进行新颖的、与人类学相关的考古学研究。阿米蒂奇和她的团队试图通过对岩石绘画样本、煅烧的骨头和纺织品碎片的比较研究，证明用PCO样品制备的AMS年代的准确性、精确性和最小样本量。他们的工作将有助于理解化学预处理对用这种方法测定年代的样品的影响，并改进这种方法，使其能够得到更广泛的应用。拟议的项目将调查PCO方法的基本局限性，以便优化其在其他方面难以确定考古材料日期的使用。该项目采用AMS放射性碳分析方法，对这些类型的样品进行可靠的测年，以最小的破坏性和快速的方法进行检验。提案目标的成功实现将提高测定考古材料年代的能力。该团队试图通过比较测量和化学分析来验证PCO作为AMS放射性碳分析的样品制备方法。该项目的成果将通过会议研讨会、讲习班和书籍传播，向人类学考古学家和物理科学家等不同受众传播该项目的成果。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Knowing the age of ancient artifacts helps archaeologists better place human activities into absolute time frames. Radiocarbon dating is one of the most important developments in archaeology from the 20th century, making it possible to directly date materials from the past. However, many artifacts are too small or fragile to survive the standard methods for preparing samples for radiocarbon dating. Dr. Ruth Ann Armitage, of Eastern Michigan University, and her team of collaborating archaeologists and students will evaluate the use of plasma chemical oxidation (PCO) for preparing samples of small, fragmentary or fragile artifacts for radiocarbon dating by accelerator mass spectrometry (AMS). The focus of the project is dating endangered rock art, burned bone, and fragments shed from fragile textiles that would otherwise be difficult or impossible to radiocarbon date directly. PCO has been used for decades as a way to extract organic carbon from inorganic carbon matrices to date rock paintings. It is also a way to date fragile organic materials without destroying them, allowing for repeated dating of the same sample. However, much remains to be learned about the capabilities and limitations of the PCO technique. Validation of the PCO method is critical to applying it in a meaningful way to answer questions about the age of artifacts that might otherwise be overlooked. The Armitage group has a long track record of collaborative work between chemists and archaeologists to better understand past human society and behavior through radiocarbon dating and chemical analysis of artifacts. This project will develop a method for handling, processing and radiocarbon dating archaeological samples that could not be dated otherwise, adding to what is known about people and their activities in the past. The award supports a diverse group of scientists and students at a predominantly undergraduate institution (PUI) doing novel, anthropologically-relevant archaeology research in collaboration with archaeologists.Dr. Armitage and her team seek to demonstrate the accuracy, precision and minimum sample size that can be AMS dated with PCO sample preparation through comparative studies of rock painting samples, calcined bones, and textile fragments. Their work will aid in understanding the effects of chemical pretreatments on samples dated in this way, as well as improving the method so that it can become more widely applicable. The proposed project will investigate the fundamental limitations of the PCO method in order to optimize its use for otherwise difficult to date archaeological materials. The project examines minimally-destructive and rapid methods for reliably dating these types of samples with AMS radiocarbon analysis. Successful completion of the proposal's objectives will improve the ability to date archeological materials. The team seeks to validate PCO as a sample preparation method for AMS radiocarbon analysis through comparative measurements and chemical analysis. The project results will be disseminated through a conference symposium, workshop, and book to disseminate the results of the project to a diverse audience of anthropological archaeologists and physical scientists.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.