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Distorted powder lineshapes in 27 Al CP / MAS NMR spectroscopy of solids

✍ Scribed by Patrick J. Barrie

Publisher
Elsevier Science
Year
1993
Tongue
English
Weight
421 KB
Volume
208
Category
Article
ISSN
0009-2614

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✦ Synopsis

spectra of aluminium acetylacetonate show distinct lineshapes depending on the experimental conditions as the different orientations within the powder cross-polarize with differmg efficiencies. Selective polarization transfer to the l/2++-l/2 transition occurs at rfpower levels corresponding to 3w, = c+, while non-selective polarization transfer can occur at higher 27A1 rfpowers. Two-dimensional quadrupole nutation spectra show that the cross-polarization lineshapes arise principally because the different orientations have different 27Al nutation frequencies. The results obtained highlight the caution needed in the interpretation of CP/MAS NMR spectra of quadrupolar nuclei.

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