Improved quantitation in 3QMAS of spin 52 nuclei by RF power modulation of FAM-II

High-resolution NMR of quadrupolar I=52 nuclei using triple-quantum magic angle spinning (3QMAS) techniques can provide more accurate quantitative information on sites with small quadrupolar coupling constants by changing the pulse strength in addition to the pulse length in the FAM-II multiple-quantum conversion sequence. These effects are illustrated using 27Al NMR of yttrium aluminium garnet and andalusite.