Variable‐angle sample‐spinning high resolution NMR of solids
Variable‐angle sample‐spinning high resolution NMR of solids
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固体的可变角度样品旋转高分辨率核磁共振
DOI：
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发表时间：
1982
期刊：
影响因子：
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通讯作者：
E. Oldfield
中科院分区：
文献类型：
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作者：
S. Ganapathy;S. Schramm;E. Oldfield
我们在“魔角”样品旋转（MASS）和“变角”样品旋转（VASS）条件下获得了多种非整数自旋四极核（23 Na、51 V和55 Mn）的高分辨率固态核磁共振谱。我们表明，对于二阶四极相互作用主导（1/2，−1/2）自旋跃迁宽度的系统，最佳谱线变窄是通过在熟悉的θ=54.7°“魔角”以外的角度快速旋转样品来实现的。该效应源于二阶四极相互作用的更复杂的角度依赖性，而不是偶极和化学位移相互作用的更熟悉的P2（cos θ）依赖性，并且给出了各种旋转角的理论VASS线形和电场梯度张量不对称参数（η）。我们表明，在低场的VASS NMR产生复杂的谱线形状，在某些角度表现出良好的解决中心带和旋转边带。我们还简要地讨论了与示例.
We have obtained high‐resolution solid‐state NMR spectra of a variety of nonintegral‐spin quadrupolar nuclei (23Na, 51V, and 55Mn) under conditions of ‘‘magic‐angle’’ sample‐spinning (MASS) and ‘‘variable‐angle’’ sample‐spinning (VASS). We show for systems in which the second‐order quadrupole interaction dominates the breadth of the (1/2,−1/2) spin transition, that optimum line narrowing is achieved by rapid sample rotation at angles other than the familiar θ=54.7° ‘‘magic‐angle.’’ The effect originates in the more complex angle dependence of the second‐order quadrupole interaction, rather than the more familiar P2 (cos θ) dependence of dipolar and chemical shift interactions, and theoretical VASS line shapes for a variety of spinning angles, and electric field gradient tensor asymmetry parameters (η), are presented. We show that VASS NMR at low fields generates complex spectral line shapes, which at some angles exhibit well‐resolved centerbands and spinning sidebands. We also discuss briefly, with exampl...