论文标题
静态固体中磁共振中极化转移机制的统一描述：交叉极化和DNP
A Unified Description for Polarization-Transfer Mechanisms in Magnetic Resonance in Static Solids: Cross Polarization and DNP
论文作者
论文摘要
极化转移是磁共振实验中的至关重要的构件，即，它们可用于极敏感核并将多维NMR光谱中的核自旋相关联。极化可以在不同的核自旋物种上转移，也可以从电子旋转到相对较低的核自旋。可以通过交叉极化（CP）进行固态NMR（SSNMR）中的以前的路线，而后一种路线被称为动态核极化（DNP）。尽管操作条件不同，但我们认为这两种机制在理想条件下都是相似的过程，即电子只是另一个具有更高旋转磁比的旋转1/2粒子。在这里，我们表明，可以使用基于平均哈密顿理论（AHT）与虚拟运营商结合使用的统一理论来描述CP和DNP过程。直观而统一的方法允许对交叉效应（CE）DNP机制的新见解，从而更好地设计了DNP偏振剂，并扩展了应用不仅仅是超极化。我们探讨了利用理论上预测的DNP瞬变的可能性，用于电子核孔距离测量值 - 固态NMR中的类似常规偶极 - 偶联实验。
Polarization transfers are crucial building blocks in magnetic resonance experiments, i.e., they can be used to polarize insensitive nuclei and correlate nuclear spins in multidimensional NMR spectroscopy. The polarization can be transferred either across different nuclear spin species or from electron spins to the relatively low-polarized nuclear spins. The former route occurring in solid-state NMR (ssNMR) can be performed via cross polarization (CP), while the latter route is known as dynamic nuclear polarization (DNP). Despite having different operating conditions, we opinionate that both mechanisms are theoretically similar processes in ideal conditions, i.e., the electron is merely another spin-1/2 particle with a much higher gyromagnetic ratio. Here, we show that the CP and DNP processes can be described using a unified theory based on average Hamiltonian theory (AHT) combined with fictitious operators. The intuitive and unified approach has allowed new insights on the cross effect (CE) DNP mechanism, leading to better design of DNP polarizing agents and extending the applications beyond just hyperpolarization. We explore the possibility of exploiting theoretically predicted DNP transients for electron-nucleus distance measurements--like routine dipolar-recoupling experiments in solid-state NMR.
