Nuclear Magnetic Resonance Methods for Non-Crystalline Solids

在这个由化学部门化学测量和成像项目资助的项目中，俄亥俄州立大学的Philip Grandinetti教授将开发新的核磁共振（NMR）方法来阐明非晶体材料的结构。这些材料在不同层次上的原子结构有许多未解决的问题，从短距离，即第一配位球结构分布，到中距离，如链和环的尺寸统计。核磁共振可以单独提供所有这些层面的信息，也可以与其他测量或建模相辅相成。然而，要做到这一点，需要做大量的工作来建立方法的基础设施，并充分理解核磁共振参数和结构之间的关系。本项目所获得的结构分布对于确定玻璃和熔体的热力学模型、离子输运模型，以及在玻璃结构和动力学的分子动力学模拟中具有重要价值。这些细节可以产生深远的影响。例如，放射性废物通常被混合到玻璃熔体中进行长期封存，环境政策决定将需要关于玻璃作为储存材料的长期有效性的准确科学数据，这反过来又需要对强烈依赖于原子水平结构的传输特性有更深入的了解。这些新方法也将影响其他领域，如陶瓷、催化剂、生物聚合物，这些领域可以利用为我们的应用开发的相同资源和方法。该项目的长期目标是为材料科学家创建标准的核磁共振协议和软件，使他们能够获得足够的原子和分子水平结构统计数据来设计和合成新材料。除了材料科学应用之外，该项目中开发的对固体中四极核进行选择性核磁共振激发的方法甚至可以用于磁共振成像的对比，并最终可能导致改善医疗诊断和治疗。因此，人们可以期望这些磁共振方法中的许多将被纳入商业产品。在这个项目中接受培训的学生包括各种代表性不足的群体的成员。

In this project, funded by the Chemical Measurement and Imaging Program of the Chemistry Division, Professor Philip Grandinetti of the Ohio State University will develop new nuclear magnetic resonance (NMR) methods for elucidating structure in non-crystalline materials. There are many unresolved questions in these materials regarding atomic structure at different levels, from short range, i.e., first coordination sphere structural distributions, to intermediate range, e.g., chain and ring size statistics. It is possible for NMR to provide information at all these levels, either alone, or complemented by other measurements or modeling. To do this, however, much work is needed to build up an infrastructure of methods and a full understanding of the relationships between NMR parameters and structure. Structural distributions obtained in this project will be valuable in confirming thermodynamic models of glasses and melts, models for ionic transport, and also in refining potentials in molecular dynamics simulations of structure and dynamics in glasses. Such details can have far reaching impact. For example, radioactive waste is commonly mixed into glass melts for long term containment, and environmental policy decisions will require accurate scientific data on the long term effectiveness of glass as a storage material, which in turn, will require a deeper understanding of transport properties that depends strongly on the atomic level structure. These new methodologies will also impact other fields such as ceramics, catalysts, biopolymers, which can utilize the same resources and methodology developed for our applications. The long term goal of this project is to create standard NMR protocols and software for materials scientists enabling them to obtain enough atomic and molecular level structure statistics to design and synthesize new materials. Beyond materials science applications, methods developed in this project for selective NMR excitation of quadrupolar nuclei in solids can even be used for contrast in magnetic resonance imaging, and could eventually lead to improved medical diagnosis and treatment. As such, one can expect a number of these magnetic resonance methodologies to be incorporated into commercial products. Students trained in this project include members of various under-represented groups.