论文标题
基于对称性的单线 - 三个三重激发溶液核磁共振
Symmetry-Based Singlet-Triplet Excitation in Solution Nuclear Magnetic Resonance
论文作者
论文摘要
耦合成对的自旋1/2核支持一个单线状态和三个三重态。在许多情况下，核单线秩序定义为单人群人群与三胞胎人群平均值之间的差异，是一个长期存在的状态，在解决方案方面持续了很长时间。已经提出了从核磁化开始的各种方法来产生单线顺序。这就需要通过调制射频场刺激单线到三杆的跃迁。我们表明，最近描述的脉冲序列，称为PulsePol（Schwartz $ \ textit {et al。} $，Science Advances，$ \ textbf {4} $，EAAT8978（2018）和Arxiv：1710.01508）是一种将磁性转化为长期启动的单句的有效技术。我们表明，可以通过在魔法旋转固态NMR中调整基于对称性的重耦序列的理论来理解该脉冲序列的运行。即兴即兴的概念允许使用基于对称性的脉冲序列理论来解释Pulsepol，并解释其稳健性。该理论用于得出一系列新的脉冲序列，用于执行溶液NMR中的单线 - 三个脉冲激发和转换。展示了用于进一步增强转化鲁棒性的方案。
Coupled pairs of spin-1/2 nuclei support one singlet state and three triplet states. In many circumstances the nuclear singlet order, defined as the difference between the singlet population and the mean of the triplet populations, is a long-lived state which persists for a relatively long time in solution. Various methods have been proposed for generating singlet order, starting from nuclear magnetization. This requires the stimulation of singlet-to-triplet transitions by modulated radiofrequency fields. We show that a recently described pulse sequence, known as PulsePol (Schwartz $\textit{et al.}$, Science Advances, $\textbf{4}$, eaat8978 (2018) and arXiv:1710.01508), is an efficient technique for converting magnetization into long-lived singlet order. We show that the operation of this pulse sequence may be understood by adapting the theory of symmetry-based recoupling sequences in magic-angle-spinning solid-state NMR. The concept of riffling allows PulsePol to be interpreted using the theory of symmetry-based pulse sequences, and explains its robustness. This theory is used to derive a range of new pulse sequences for performing singlet-triplet excitation and conversion in solution NMR. Schemes for further enhancing the robustness of the transformations are demonstrated.
