New NMR Methods for Investigating Structure in Inorganic Oxide Glasses

俄亥俄州州立大学的Philip J. Grandinetti博士获得了化学部物理化学计划的资助，用于研究无机氧化物玻璃结构的新核磁共振方法。 先进的魔角旋转（MAS）技术，如转子辅助极化转移（RAPT）和快速旋转，在旋转共振（FASTER），在俄亥俄州州立大学和其他地方开发的转移增强将被完善的应用，在玻璃结构的测定。 RAPT四极灵敏度增强计划将得到改进，以获得最大的增强范围广泛的自旋耦合和共振偏移，并获得RAPT增强版本的动态角自旋（DAS）和多量子（MQ）-MAS。为了将FASTER与其他MQ-MAS方法进行比较，将对FASTER旋转共振对核自旋、四极耦合、不对称性和化学位移等参数的依赖性进行数值和实验研究。 DAS和MQ-MAS的灵敏度增强版本将用于研究二元（金属氧化物硅酸盐）和三元（金属氧化物硅酸盐）玻璃组合物，以期量化Si-O-Si键角、配位数以及桥氧和非桥氧周围的几何形状。从这项研究中获得的对无机氧化物玻璃的理解将影响多个领域的研究人员。 固体核磁共振方法在结构测定中的潜在重要性长期以来一直受到灵敏度问题的阻碍。 格兰迪内蒂博士的小组和其他人的成就正在克服这些问题中的许多问题，俄亥俄州州立大学的研究将进一步克服这些问题。 为提高固态NMR灵敏度而开发的方法将对希望充分利用四极核作为结构探针的研究人员产生广泛的影响。

Dr. Philip J. Grandinetti of Ohio State University is funded for his research on new NMR methods for investigating structure in inorganic oxide glasses by the Physical Chemistry Program of the Chemistry Division. Advanced magic angle spinning (MAS) techniques, such as rotor assisted polarization transfer (RAPT) and fast spinning gives transfer enhancement at rotary resonance (FASTER), developed at Ohio State University and elsewhere will be refined for applications to structural determinations in glasses. RAPT quadrupolar sensitivity enhancement schemes will be refined for obtaining maximal enhancements for a wide range of spin couplings and resonant offsets, and for obtaining RAPT enhanced versions of dynamic-angle spinning (DAS) and multiple-quantum (MQ)-MAS. Numerical and experimental studies of the dependence of the FASTER rotary resonances on parameters such as nuclear spin, quadrupolar coupling, asymmetry, and chemical shifts will be done in order to compare FASTER with other MQ-MAS methods. Sensitivity enhanced versions of DAS and MQ-MAS will be used to study binary (metal oxide silicates ) and ternary (bimetal oxide silicates) glass compositions, with a view towards quantifying Si-O-Si bond angles, coordination numbers, and geometries around bridging and non-bridging oxygens.The understanding of inorganic oxide glasses obtained from this research will impact researchers in several areas. The potential importance of solid-state NMR methods in structure determinations has long been thwarted by sensitivity issues. Many of these issues are being overcome by accomplishments from Dr. Grandinetti's group and by others, and will be further overcome by the the research done at Ohio State University. The methods that will be developed for enhancing solid-state NMR sensitivity will have a broad impact on researchers wanting to take full advantage of quadrupolar nuclei as structural probes.