Half-integer-spin quadrupolar nuclei in magic-angle spinning paramagnetic NMR : The case of NaMnO2

• A combination of solid-state NMR methods for the extraction of shift and quadrupolar parameters for half-integer nuclei in the structurally complex NaMnO2 Na-ion cathode material, under magic-angle spinning (MAS) is presented. We show that the integration of the Magic-Angle Turning experiment with Rotor-Assisted Population transfer can be used both to identify shifts and to extract a range of magnitudes for their quadrupolar coupling. We also demonstrate the applicability of the the two-dimensional one pulse (TOP) based double-sheared Satellite Transition Magic-Angle Spinning (TOP-STMAS) showing how it can yield a spectrum with separated shift and second-order quadrupolar anisotropies, which in turn can be used to analyse a quadrupolar lineshape free of bulk magnetic susceptibility induced shift dispersion and determine both isotropic shift and quadrupolar products. Combining all these experiments, the shift and quadrupolar parameters for all observed Na environments were extracted and yielded excellent agreement with the density functional theory (DFT) based models that were reported in previous literature. We expect these methods to open the door for new possibilities for solid-state NMR to probe half-integer quadrupolar nuclei in paramagnetic materials and other systems exhibiting large shift dispersion. 

Ämnesord

NATURVETENSKAP  -- Kemi -- Fysikalisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Physical Chemistry (hsv//eng)

Nyckelord

Paramagnetic NMR

Solid-state NMR

Magic-angle spinning

Quadrupolar interaction

TOP-STMAS

RAPT

MAT

Physical Chemistry

fysikalisk kemi

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