MAS-DNP Enhancements: Hyperpolarization, Depolarization, and Absolute Sensitivity
MAS-DNP Enhancements: Hyperpolarization, Depolarization, and Absolute Sensitivity
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DOI：
10.1002/9780470034590.emrstm1559
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发表时间：
2018-01-01
期刊：
影响因子：
--
通讯作者：
De Paepe, Gael
中科院分区：
文献类型：
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作者：
Hediger, Sabine;Lee, Daniel;De Paepe, Gael
在过去的几十年里，高磁场下的动态核极化已经取得了重大进展，这种超极化技术目前正在彻底改变固态NMR对化学，材料科学和生物学中复杂系统研究的影响。在本文中，我们强调的重要性和困难，量化从DNP在魔角旋转的灵敏度。为此，我们提供了深入了解交叉效应，目前主要的MAS-DNP机制。这包括微波诱导的超极化现象的描述，但也减少了NMR信号的微波照射前掺杂有极化剂的样品（漂白和去极化效应）。我们强调了核超极化建立时间在评估MAS-DNP效率中的重要性。最后，我们讨论了影响DNP增强光谱灵敏度的其他实验参数，并根据调查类型提出了适当表征的指导方针。
Dynamic nuclear polarization at high magnetic fields has made significant progress over the last decades, and this hyperpolarizing technique is currently revolutionizing the impact of solid-state NMR for the study of complex systems in chemistry, material science, and biology. In this article, we emphasize the importance and difficulty in quantifying sensitivity from DNP under magic-angle spinning. To this end, we provide insight into the cross effect, the current main MAS-DNP mechanism. This includes a description of the microwave-induced hyperpolarization phenomenon but also of the reduction of the NMR signal prior to microwave irradiation for samples doped with polarizing agents (bleaching and depolarization effects). We highlight the importance of the nuclear hyperpolarization buildup time in the evaluation of MAS-DNP efficiency. Finally, we discuss other experimental parameters affecting sensitivity in DNP-enhanced spectra and propose a guideline for its proper characterization depending on the type of investigation.