Performance of the cross-polarization experiment in conditions of radiofrequency field inhomogeneity and slow to ultrafast magic angle spinning (MAS)
<p>In this paper, we provide an analytical description of the performance of the cross-polarization (CP) experiment, including linear ramps and adiabatic tangential sweeps, using effective Hamiltonians and simple rotations in 3D space. It is shown that radiofrequency field inhomogeneity induce...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-08-01
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| Series: | Magnetic Resonance |
| Online Access: | https://mr.copernicus.org/articles/4/199/2023/mr-4-199-2023.pdf |
| Summary: | <p>In this paper, we provide an analytical description of the performance of the cross-polarization (CP) experiment, including linear ramps and
adiabatic tangential sweeps, using effective Hamiltonians and simple rotations in 3D space. It is shown that radiofrequency field inhomogeneity
induces a reduction in the transfer efficiency at increasing magic angle spinning (MAS) frequencies for both the ramp and the adiabatic CP experiments. The effect depends
on the ratio of the dipolar coupling constant and the sample rotation frequency. In particular, our simulations show that for small dipolar
couplings (1 <span class="inline-formula">kHz</span>) and ultrafast MAS (above 100 <span class="inline-formula">kHz</span>) the transfer efficiency is below 40 % when extended contact times up to
20 <span class="inline-formula">ms</span> are used and relaxation losses are ignored. New recoupling and magnetization transfer techniques that are designed explicitly to
account for inhomogeneous radiofrequency fields are needed.</p> |
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| ISSN: | 2699-0016 |