Determination of spin-5/2 quadrupolar coupling with two-pulse sequences.
The density matrix of a spin-5/2 system excited by two in-phase pulses separated by a delay tau 2 is calculated from the equilibrium state to the end of the second pulse. The interaction involved throughout the computation is the first-order quadrupolar interaction. Consequently, the results are valid for any ratio of the quadrupolar coupling to the amplitude of the radio-frequency pulse. It is shown that single- and multi-quantum coherences developed during the first pulse are detected at the end of the second pulse through single-quantum coherences. Other two-pulse sequences with various phase cyclings as well as the rotary echo sequence are also discussed and illustrated with the nuclei 27Al in a single crystal of corundum Al2O3.
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Laboratoire de Chimie des Surfaces, CNRS URA 1428, Université Pierre et Marie Curie, Paris, France.
D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D012984:Software