FTIR Spectroscopy of CO3- and OH-bearing Apatites

磷灰石族矿物主要由钙和磷酸盐组成，含有少量的氯、氟、氢氧化物、碳酸盐和硫酸盐。这些次要成分可以通过数学模型与气体(例如水和二氧化碳)联系起来，这些气体在许多地质过程中都很重要，这些过程不仅导致矿藏的形成，而且还导致火山爆发的原因。磷灰石存在于各种各样的岩石中。因此，这项研究将为建立基于磷灰石的从地幔到地表的(固体或熔融的)岩石中二氧化碳和水的行为的数学模型提供分析和智力基础。一个潜在的应用是确定与气候变化相关的地质时期火山对大气中二氧化碳的贡献。这项研究的更广泛影响在于它作为北卡罗来纳州自然科学博物馆自然研究中心不可分割的一部分，该中心是一个8万平方英尺的设施，旨在通过各种论坛和媒体将研究直接带给普通公众。预计在理解牙齿和骨骼磷灰石中加入碳酸盐以及生物材料的设计方面将产生进一步的影响。这项研究解决了磷灰石类矿物的基本问题，使用微观分析技术来增强数学模型中使用的热力学数据。该项目将包括开发磷灰石的微量分析方法，如傅里叶变换红外光谱(FTIR)与二次离子质谱仪(SIMS)相结合测量OH(羟基离子)和CO3(碳酸盐基团)。将进一步研究电子探针显微分析(EPMA)过程中氟和氯在磷灰石中的扩散。磷灰石将在600-800°C的熔融盐中合成，提供了一个简单的系统来测定纯端元磷灰石、含氟、氯和羟基离子混合物以及羟基离子和碳酸盐混合物的(数学)热力学数据。

Apatite group minerals are made primarily of calcium and phosphate and contain smaller amounts of chlorine, fluorine, hydroxide, carbonate and sulfate. These minor components can be linked through mathematical models to gases (for example, water and carbon dioxide) that are important in many geological processes that lead not only to formation of ore deposits but also to the causes for explosive volcanism. Apatites are found in a wide variety of rocks. Therefore this study will provide the analytical and intellectual basis for an apatite-based mathematical model for carbon dioxide and water behavior in (solid or molten) rocks from the Earth's mantle to surface. One potential application is determining carbon dioxide contributions from volcanoes into the atmosphere at geologic times associated with climate change. A broader impact of this research lies in its presentation as an integral part of the North Carolina Museum of Natural Sciences' Nature Research Center, an 80,000 square foot facility designed to bring research directly to the general public through a variety of forums and media. Further impact is expected in the understanding of carbonate incorporated into tooth and bone apatite, and in the design of biomaterials. This research addresses fundamental problems with the apatite group minerals, using microanalytical techniques to enhance the thermodynamic data used in mathematical models. The project will include the development of microanalytical methods for apatites such as Fourier Transform Infrared Spectroscopy (FTIR) for the measurement of OH (hydroxyl ion) and CO3 (carbonate group) in combination with Secondary Ion Mass Spectrometry (SIMS). Diffusion of fluorine and chlorine in apatite during Electron Probe Microanalysis (EPMA) will be further examined. Apatites will be synthesized in molten salts at temperatures from 600-800°C, providing a simple system for determining (mathematical) thermodynamic data for the pure end member apatites and for the apatites containing mixtures of fluorine, chlorine and hydroxyl ions, and mixtures of hydroxyl ions and carbonate.