Heteronuclear dipolar recoupling of half-integer quadrupole nuclei under fast magic angle spinning

Area of Science:

• Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy
• Materials Science
• Quantum Information Science

Background:

• Heteronuclear dipolar recoupling is crucial for structural elucidation in solid materials.
• Half-integer quadrupole nuclei present challenges in NMR due to their complex interactions.
• Existing methods may lack resolution or applicability under dynamic conditions.

Purpose of the Study:

• To develop and validate a novel experimental method for heteronuclear dipolar recoupling of half-integer quadrupole nuclei.
• To enable the extraction of accurate structural parameters under fast magic-angle spinning (MAS).
• To provide a high-resolution technique for materials characterization.

Main Methods:

• Manipulation of the central transition using spin-polarization-inversion rotary resonance.
• Application of average Hamiltonian theory and numerical simulations for validation.
• Analysis of rotational-echo dephasing and estimation of heteronuclear van Vleck second moment.

Main Results:

• The proposed method effectively recouples heteronuclear dipolar interactions in half-integer quadrupole nuclei.
• Initial rotational-echo dephasing is approximated by a parabolic function, allowing estimation of the second moment.
• A correction factor, independent of geometry and spin system order, accounts for quadrupolar coupling effects.

Conclusions:

• The developed method facilitates structural characterization of materials containing half-integer quadrupole nuclei.
• High-resolution structural information can be obtained under fast MAS conditions.
• Experimental validation on aluminophosphate systems (AlPO(4)-5 and AlPO(4)-11) confirms the method's efficacy.