Department of Physics, University of California at Berkeley, Berkeley, California 94720-7300, USA.
Phys Rev Lett. 2011 Sep 2;107(10):107601. doi: 10.1103/PhysRevLett.107.107601. Epub 2011 Sep 1.
We investigate nuclear magnetic resonance (NMR) in near zero field, where the Zeeman interaction can be treated as a perturbation to the electron mediated scalar interaction (J coupling). This is in stark contrast to the high-field case, where heteronuclear J couplings are normally treated as a small perturbation. We show that the presence of very small magnetic fields results in splitting of the zero-field NMR lines, imparting considerable additional information to the pure zero-field spectra. Experimental results are in good agreement with first-order perturbation theory and with full numerical simulation when perturbation theory breaks down. We present simple rules for understanding the splitting patterns in near-zero-field NMR, which can be applied to molecules with nontrivial spectra.
我们研究了近零磁场中的核磁共振（NMR），其中塞曼相互作用可以被视为电子介导的标量相互作用（J 耦合）的微扰。这与高场情况形成鲜明对比，在高场情况下，通常将异核 J 耦合视为小微扰。我们表明，非常小的磁场的存在导致零场 NMR 线的分裂，为纯零场光谱提供了相当多的附加信息。实验结果与一级微扰理论以及当微扰理论失效时的全数值模拟吻合良好。我们提出了理解近零场 NMR 中分裂模式的简单规则，这些规则可应用于具有复杂光谱的分子。
