Solid-state gallium-69 and gallium-71 nuclear magnetic resonance spectroscopic studies of gallium analog zeolites and related systems

The authors have obtained solid-state 11.7-T /sup 69/Ga and /sup 71/Ga nuclear magnetic resonance (NMR) spectra of a series of gallosilicates (gallium analogues of zeolites Na-X, Na-Y, Na-sodalite, and Na-natrolite). From the apparent /sup 69/Ga and /sup 71/Ga chemical shifts, values of the nuclear quadrupole coupling constants (e/sup 2/qQ/h) and the true, isotropic chemical shifts (delta/sub i) have been deduced for the framework, tetrahedral, Ga(OSi)/sub 4/ sites. The e/sup 2/qQ/h values are in the range 1.9-2.7 MHz for /sup 69/Ga and 1.2-1.7 MHz for /sup 71/Ga. The isotropic chemical shifts are all in the range 171-186 ppm downfield from an external standard of 1 M Ga(NO/sub 3/)/sub 3/. Their results indicate that measurement of the apparent (second-order shifted) chemical shifts for pairs of isotopes of nonintegral spin quadrupolar nuclei in solids at one magnetic field strength is a useful new approach for determination of both isotropic chemical shifts and nuclear quadrupole coupling constant values.