New NMR Methods for Investigating Structure in Inorganic Oxide Glasses

Ohio State University Research Foundation -Do Not Use, Columbus OH

Investigators

Abstract

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.