Performance of the cross-polarization experiment in conditions of radiofrequency field inhomogeneity and slow to ultrafast magic angle spinning (MAS).

Q3 Physics and Astronomy
Magnetic resonance (Gottingen, Germany) Pub Date : 2023-08-15 eCollection Date: 2023-01-01 DOI:10.5194/mr-4-199-2023
Andrej Šmelko, Jan Blahut, Bernd Reif, Zdeněk Tošner
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引用次数: 0

Abstract

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 kHz) and ultrafast MAS (above 100 kHz) the transfer efficiency is below 40 % when extended contact times up to 20 ms 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.

射频场不均匀和慢速到超快魔角自旋(MAS)条件下的交叉极化实验性能
摘要在本文中,我们使用有效的哈密顿量和三维空间中的简单旋转,对交叉极化(CP)实验的性能进行了分析描述,包括线性斜坡和非绝热切向扫描。研究表明,在斜坡和绝热CP实验中,射频场的不均匀性会导致魔角自旋(MAS)频率增加时的传输效率降低。该效应取决于偶极耦合常数与样品旋转频率的比值。特别是,我们的模拟表明,对于小偶极子耦合(1 kHz)和超快MAS(高于100 kHz)时,传输效率低于40 % 当延长接触时间达到20 使用ms并且忽略弛豫损失。需要新的重新耦合和磁化转移技术,这些技术被明确设计为考虑不均匀的射频场。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
4.50
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审稿时长
14 weeks
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