Enhanced resolution and quantitation from `ultrahighʹ field NMR spectroscopy of glasses

The utilization of higher magnetic fields for nuclear magnetic resonance (NMR) (e.g., 14.1 and 18.8 T) can enhance both resolution and sensitivity in studies of disordered materials. When used in conjunction with fast magic angle spinning (MAS), high-field NMR can yield structural information not always available from NMR experiments of glasses at lower fields. Examples include site distinction of multiple boron groupings in 11B MAS NMR spectra of borate glasses, the spectroscopic observation of low concentrations of five- and six-co-ordinate aluminum species in 27Al MAS NMR spectra of aluminosilicate glasses, and new insight into magnesium co-ordination environments in silicate glasses using 25Mg MAS NMR. Also presented are 17O MAS NMR spectra of a zeolite in which high-field experiments permit resolution and quantification of bound molecular water. Comparisons of spectral data collected at 18.8 T with those at lower fields demonstrate these principles and indicate the potential of high-field MAS NMR applications to amorphous solids.