论文标题
无微波J驱动的DNP（MF-JDNP）：提高溶液状态NMR灵敏度的建议
Microwave-free J-driven DNP (MF-JDNP): A proposal for enhancing the sensitivity of solution-state NMR
论文作者
论文摘要
最近提出了J驱动的动力学核极化（JDNP），以增强溶液状态核磁共振（NMR）的灵敏度，同时绕过在分析应用中有磁性的磁场上传统（过肝）DNP所面临的局限性。像Overhauser DNP一样，JDNP还需要使用高频微波炉饱和电子极化，该电子极化在大多数液体中已知渗透差和相关的加热效应。目前的无微波JDNP（MF-JDNP）提案旨在通过将样品在较高磁场和较低磁场之间穿梭样品来增强溶液状态NMR的灵敏度，其中其中一个提供了与电子间频率相匹配的电子Larmor频率。如果旋转足够快地穿越了所谓的JDNP条件，我们预计将在没有微波辐照的情况下产生相当大的核极化。该MF-JDNP提案需要自由基，其单线/三胞胎自我释放率由偶极性高精细弛豫和可以与这些电子弛豫过程竞争的穿梭时间主导。这种沟通讨论了MF-JDNP背后的理论，以及对激进分子和条件的建议，可以使这种新的NMR敏感性增强。
J-driven Dynamic Nuclear Polarization (JDNP) was recently proposed for enhancing the sensitivity of solution-state nuclear magnetic resonance (NMR), while bypassing the limitations faced by conventional (Overhauser) DNP at magnetic fields of interest in analytical applications. Like Overhauser DNP, JDNP also requires saturating the electronic polarization using high-frequency microwaves, known to have poor penetration and associated heating effects in most liquids. The present microwave-free JDNP (MF-JDNP) proposal seeks to enhance the sensitivity of the solution state NMR by shuttling the sample between higher and lower magnetic fields, with one of these fields providing an electron Larmor frequency that matches the inter-electron exchange coupling Jex. If spins cross this so-called JDNP condition sufficiently fast, we predict that a sizable nuclear polarization will be created without microwave irradiation. This MF-JDNP proposal requires radicals whose singlet/triplet self-relaxation rates are dominated by dipolar hyperfine relaxation, and shuttling times that can compete with these electron relaxation processes. This communication discusses the theory behind the MF-JDNP, as well as proposals for radicals and conditions that could enable this new approach to NMR sensitivity enhancement.
