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Interaction frames in solid-state NMR: A case study for chemical-shift-selective irradiation schemes
Solid State Nuclear Magnetic Resonance ( IF 1.8 ) Pub Date : 2022-10-18 , DOI: 10.1016/j.ssnmr.2022.101834
Matías Chávez 1 , Matthias Ernst 1
Affiliation  

Interaction frames play an important role in describing and understanding experimental schemes in magnetic resonance. They are often used to eliminate dominating parts of the spin Hamiltonian, e.g., the Zeeman Hamiltonian in the usual (Zeeman) rotating frame, or the radio-frequency-field (rf) Hamiltonian to describe the efficiency of decoupling or recoupling sequences. Going into an interaction frame can also make parts of a time-dependent Hamiltonian time independent like the rf-field Hamiltonian in the usual (Zeeman) rotating frame. Eliminating the dominant term often allows a better understanding of the details of the spin dynamics. Going into an interaction frame can also reduces the energy-level splitting in the Hamiltonian leading to a faster convergence of perturbation expansions, average Hamiltonian, or Floquet theory. Often, there is no obvious choice of the interaction frame to use but some can be more convenient than others. Using the example of frequency-selective dipolar recoupling, we discuss the differences, advantages, and disadvantages of different choices of interaction frames. They always include the complete radio-frequency Hamiltonian but can also contain the chemical shifts of the spins and may or may not contain the effective fields over one cycle of the pulse sequence.



中文翻译:

固态 NMR 中的相互作用框架:化学位移选择性辐照方案的案例研究

交互框架在描述和理解磁共振实验方案方面起着重要作用。它们通常用于消除自旋哈密顿量的主要部分,例如,通常 (Zeeman) 旋转坐标系中的塞曼哈密顿量,或射频场 (rf) 哈密顿量,以描述去耦或再耦合序列的效率。进入相互作用框架还可以使依赖于时间的哈密顿量的部分时间独立,就像通常(塞曼)旋转框架中的射频场哈密顿量一样。消除主导项通常可以更好地理解自旋动力学的细节。进入相互作用框架还可以减少哈密顿量中的能级分裂,从而导致扰动展开、平均哈密顿量或 Floquet 理论更快收敛。经常,没有明显的交互框架选择,但有些可能比其他的更方便。我们以频率选择性偶极再耦合为例,讨论了不同交互框架选择的差异、优点和缺点。它们总是包括完整的射频哈密顿量,但也可以包含自旋的化学位移,并且可能包含也可能不包含脉冲序列一个周期内的有效场。

更新日期:2022-10-18
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