29Si and 17O (Q)CPMG-MAS solid-state NMR experiments as an optimum approach for half-integer nuclei having long T1 relaxation times

A significantly reduced experiment time for half-integer nuclei with long T-1 relaxation times has been demonstrated by Si-29 CPMG-MAS or O-17 QCPMG-MAS experiments on alpha-cristobalite, a radiation damaged Zircon and O-17 enriched alpha-quartz, respectively. For Si-29 up to 37 h were saved compared to the MAS experiment using longer recycle periods (up to 3600 s) but fewer scans. The spectrum reconstructed from the echoes provides similar spectral information as the MAS spectrum. In the O-17 spectrum increased sensitivity facilitated determination of CSA in alpha-quartz at 9.4 T and points towards a method to obtain natural abundance O-17 spectra of non-cubic oxides. (C) 2002 Elsevier Science B.V. All rights reserved.