Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5406803 | Journal of Magnetic Resonance | 2009 | 10 Pages |
Abstract
We present a new application of the R221 symmetry-based dipolar recoupling scheme, for exciting directly double-quantum (2Q) coherences between the central transition of homonuclear half-integer quadrupolar nuclei. With respect to previously published 2Q-recoupling methods (M. Eden, D. Zhou, J. Yu, Chem. Phys. Lett. 431 (2006) 397), the R221 sequence is used without Ï/2 bracketing pulses and with an original super-cycling. This leads to an improved efficiency (a factor of two for spin-5/2) and to a much higher robustness to radio-frequency field inhomogeneity and resonance offset. The 2Q-coherence excitation performances are demonstrated experimentally by 27Al NMR experiments on the aluminophosphates berlinite, VPI5, AlPO4-14, and AlPO4-CJ3. The two-dimensional 2Q-1Q correlation experiments incorporating these recoupling sequences allow the observation of 2Q cross-peaks between central transitions, even at high magnetic field where the difference in offset between octahedral and tetrahedral 27Al sites exceeds 10Â kHz.
Related Topics
Physical Sciences and Engineering
Chemistry
Physical and Theoretical Chemistry
Authors
Q. Wang, B. Hu, O. Lafon, J. Trébosc, F. Deng, J.P. Amoureux,