Zheng Mingji, Xin Shaohui, Wang Qiang, Trébosc Julien, Xu Jun, Qi Guodong, Feng Ningdong, Lafon Olivier, Deng Feng
State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Centre for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, 430071, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Magn Reson Chem. 2021 Sep;59(9-10):1062-1076. doi: 10.1002/mrc.5163. Epub 2021 Apr 29.
Through-space heteronuclear correlation (D-HETCOR) experiments based on heteronuclear multiple-quantum correlation (D-HMQC) and refocused insensitive nuclei enhanced by polarization transfer (D-RINEPT) sequences have been proven to be useful approaches for the detection of the spatial proximity between half-integer quadrupolar nuclei in solids under magic-angle spinning (MAS) conditions. The corresponding pulse sequences employ coherence transfers mediated by heteronuclear dipolar interactions, which are reintroduced under MAS by radiofrequency irradiation of only one of the two correlated nuclei. We investigate herein using numerical simulations of spin dynamics and solid-state NMR experiments on magnesium aluminoborate glass how the choice of the channel to which the heteronuclear dipolar recoupling is applied affects the transfer efficiency of D-HMQC and D-RINEPT sequences between B and Al nuclei. Experimental results show that maximum transfer efficiency is achieved when the recoupling scheme is applied to the channel, for which the spin magnetization is parallel to the B axis in average.
基于异核多量子相关（D-HMQC）和通过极化转移增强的重聚焦不灵敏核（D-RINEPT）序列的空间异核相关（D-HETCOR）实验已被证明是在魔角旋转（MAS）条件下检测固体中半整数四极核之间空间邻近性的有用方法。相应的脉冲序列采用由异核偶极相互作用介导的相干转移，通过仅对两个相关核中的一个进行射频照射，在MAS下重新引入这种相互作用。我们在此使用自旋动力学的数值模拟以及对铝酸镁硼玻璃进行的固态核磁共振实验，研究应用异核偶极重新耦合的通道选择如何影响D-HMQC和D-RINEPT序列在硼和铝核之间的转移效率。实验结果表明，当将重新耦合方案应用于自旋磁化平均平行于B轴的通道时，可实现最大转移效率。
