POWRE: Microgram to Nanogram: A Study to Reduce the Sample Size of Graphitic Carbon Targets for AMS Radiocarbon Dating

目前，加速器质谱仪(AMS)技术为放射性碳研究人员提供了常规测量从500微克到1毫克石墨碳的样品的能力。使用AMS技术的放射性碳年龄测定比衰变计数法减少了几个数量级的碳需求。所需碳样本大小的减少使研究人员能够获得以前无法实际测量的样本。这项研究将集中在两种方法，以减少在超小样本范围内的AMS放射性碳测年所需的碳量。该项目有两个关键目标。第一个目标是优化微克到纳克大小的催化还原石墨碳样品的处理，用于AMS放射性碳年龄测定。第二个目标是确定最准确的方法来修正14C/13C比率，以确定污染物对这些超小样本测量比率的贡献。能够利用AMS技术，在常规基础上将所需的石墨化碳样品的数量减少到超小样品的水平，将为考古研究人员提供寻找新的科学研究领域的机会。这些包括但不限于陶片、岩画、花粉、植硅石、碎屑、植物氨基酸、来自骨骼的氨基酸、种子、木炭污迹和工具上的有机残留物。所有这些材料都是确定放射性碳年龄的候选材料，但限制因素是极少量的有机材料。来自这些来源的关键数据可以提供线索，帮助回答关于人类起源和史前文化的各种问题。古生物学、环境和古气候研究以及海洋学也将从这项研究中受益。可用于超小样本的材料包括化石骨骼和牙齿中属于放射性碳范围的氨基酸、大气气溶胶中的化合物、海洋溶解的有机碳和有孔虫。这些研究领域中的每一个都可以利用超小样本技术来收集关键数据并开发新的调查领域。POWRE计划提供的资金开辟了新的研究途径，将使职业发展和在研究界的专业地位得到实质性的提高。由于研究人员是一个非终身研究助理职位，POWRE的支持也可能有助于她的学术进步。该项目可以为科学界提供一个有用的新工具，并为研究人员提供一个机会，在一个常规研究补助金无法获得的领域做出贡献。

Currently, accelerator mass spectrometry (AMS) technology provides the radiocarbon researcher with the ability to routinely measure samples of 500 micrograms to one milligram of graphitic carbon. Radiocarbon age determinations using AMS technology reduces the carbon requirement by several orders of magnitude from decay counting methods. This reduction in the required carbon sample size has allowed researchers access to samples previously not practical to measure. This study will focus on two methods to reduce the required amount of carbon for AMS radiocarbon dating in the ultra small sample range. This project has two pivotal objectives. The first objective is to optimize the processing of microgram to nanogram-sized samples of catalytically-reduced graphitic carbon for AMS radiocarbon age determinations. The second goal is to determine the most accurate way to correct 14C/13C ratios for contaminant contribution to the measured ratios of these ultra small samples. The ability to utilize AMS technology that reduces the required amount of a graphitic carbon sample to the levels of ultra small samples on a routine basis would provide the archaeological researcher with the opportunity to seek new areas of scientific inquiry. These include but are not limited to organic residues on potsherds, rock art, pollen, phytoliths, sherd temper, plant amino acids, amino acids from bone, seeds, charcoal smudges, and organic residues on tools. All of these materials are candidates for radiocarbon age determinations but the limiting factor is the extremely small amounts of organic material. Critical data from these sources could provide clues to help answer a variety of questions about human origins and prehistoric cultures. Paleontology, environmental and paleoclimatic studies and oceanography would also benefit from this research. Material that may be used for ultra small samples include amino acids in fossil bone and teeth that fall within the range of radiocarbon, chemical compounds in atmospheric aerosols, marine dissolved organic carbon and foraminifera. Each of these research areas could utilize ultra small sample technology to gather critical data and develop new areas of inquiry. The funding provided by the POWRE program opens up new avenues of research that will allow career enhancement and substantively further professional standing with the research community. Since the investigator is in a non-tenured research associate position, POWRE support may assist in her academic advancement as well. This project could provide the scientific community with a useful new tool and offers the researcher a chance to contribute in an area not ordinarily available through regular research grants.