Heteronuclear dipolar recoupling of half-integer quadrupole nuclei under fast magic angle spinning |
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Authors: | Shin-Jong Huang Shang-Bin Liu Jerry C.C. Chan |
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Affiliation: | aDepartment of Chemistry, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 106, Taiwan, ROC;bInstitute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan, ROC |
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Abstract: | An experimental method for the heteronuclear dipolar recoupling of half-integer quadrupole nuclei is proposed. The idea is to manipulate the central transition based on the recoupling technique of spin-polarization-inversion rotary resonance. This method allows the extraction of structural parameters under fast magic-angle spinning. Its validity has been examined by the average Hamiltonian theory and numerical simulations. The initial rotational-echo dephasing arising from the dipolar evolution can be approximated by a parabolic function, from which the heteronuclear van Vleck second moment can be estimated. A factor, estimated from two-spin simulations, is required to account for the effects of the quadrupolar coupling and is rather independent of the geometry and the orders of the spin systems. Our method can facilitate the structural characterization of materials containing half-integer quadrupole nuclei under high-resolution condition. Experimental verification has been carried out on two aluminophosphate systems, namely, AlPO4-5 and AlPO4-11. |
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Keywords: | Quadrupole nuclei Heteronuclear dipolar recoupling Rotary resonance MAS NMR |
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