基于四元数的有效哈密顿量最优控制在大化学屏蔽各向异性存在下的固态核磁共振偶极重耦合
Solid-State NMR Dipolar Recoupling in Presence of Large Chemical Shielding Anisotropies by Quaternion-Based Effective Hamiltonian Optimal Control
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中文总结 AI 辅助
研究在大化学屏蔽各向异性影响下固态核磁共振偶极重耦合的问题，提出基于四元数的最优控制方法，通过单自旋操作优化有效哈密顿量，减少各向异性屏蔽影响，并给出\(^{19}F\)到\(^{13}C\)极化转移的数值和实验证明。
中文摘要 AI 辅助
偶极重耦合是魔角旋转（MAS）固态核磁共振光谱中的关键要素，重新引入的偶极-偶极耦合相互作用可提供核间距离信息，并在分辨率增强的多维实验中实现自旋间的极化转移。然而，在许多重要应用中，大的各向异性核自旋相互作用（如化学屏蔽各向异性）可能会对这些方法构成挑战。本文通过提出基于四元数的最优控制来应对这一挑战。该方法基于单自旋操作，能够优化有效哈密顿量，减少各向异性屏蔽的影响。我们还展示了在存在\(^{19}F\)化学屏蔽各向异性的情况下，\(^{19}F\)到\(^{13}C\)极化转移的数值和实验证明。
英文摘要
Dipolar recoupling is a key element in magic-angle-spinning (MAS) solid-state NMR spectroscopy with reintroduced dipole-dipole coupling interactions providing information about internuclear distances and enabling transfer of polarization between spins in resolution-enhancing multiple-dimensional experiments. Such methods may be challenged in many important applications by the presence of large anisotropic nuclear spin interactions such as chemical shielding anisotropy. In this paper, we address this challenge by presenting quaternion-based optimal control. This is founded in single-spin operations enabling optimization of effective Hamiltonians with reduced influences from anisotropic shielding. Along with the principles underlying such optimizations, we present numerical and experimental demonstration of 19F to 13C polarization transfer in presence of 19F chemical shielding anisotropy.
