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- Title
Efficient transfer of DNP‐enhanced <sup>1</sup>H magnetization to half‐integer quadrupolar nuclei in solids at moderate spinning rate.
- Authors
Nagashima, Hiroki; Trébosc, Julien; Kon, Yoshihiro; Lafon, Olivier; Amoureux, Jean‐Paul
- Abstract
We show herein how the proton magnetization enhanced by dynamic nuclear polarization (DNP) can be efficiently transferred at moderate magic‐angle spinning (MAS) frequencies to half‐integer quadrupolar nuclei, S ≥ 3/2, using the Dipolar‐mediated Refocused Insensitive Nuclei Enhanced by Polarization Transfer (D‐RINEPT) technique, in which a symmetry‐based SR412 recoupling scheme built from adiabatic inversion 1H pulses reintroduces the 1H–S dipolar couplings, while suppressing the 1H–1H ones. The use of adiabatic pulses also improves the robustness to offsets and radiofrequency (rf)‐field inhomogeneity. Furthermore, the efficiency of the polarization transfer is further improved by using 1H composite pulses and continuous‐wave irradiations between the recoupling blocks, as well as by manipulating the S satellite transitions during the first recoupling block. Furthermore, in the case of large 1H–S dipolar couplings, the D‐RINEPT variant with two pulses on the quadrupolar channel results in an improved transfer efficiency. We compare here the performances of this new adiabatic scheme with those of its parent version with single π pulses, as well as with those of PRESTO and CPMAS transfers. This comparison is performed using simulations as well as DNP‐enhanced 27Al, 95Mo, and 17O NMR experiments on isotopically unmodified γ‐alumina, hydrated titania‐supported MoO3, Mg(OH)2, and l‐histidine·HCl·H2O. The introduced RINEPT method outperforms the existing methods, both in terms of efficiency and robustness to rf‐field inhomogeneity and offset.
- Subjects
POLARIZATION (Nuclear physics); MAGIC angle spinning; MAGNETIZATION; SINGLE parents; RADIO frequency
- Publication
Magnetic Resonance in Chemistry, 2021, Vol 59, Issue 9, p920
- ISSN
0749-1581
- Publication type
Article
- DOI
10.1002/mrc.5121