Magnitudes and orientations of interaction tensors determined from rotational resonance MAS NMR lineshapes of a four-(13)C-spin system
Magnitudes and orientations of interaction tensors determined from rotational resonance MAS NMR lineshapes of a four-(13)C-spin system
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由四 (13)C 自旋系统的旋转共振 MAS NMR 线形确定的相互作用张量的大小和方向
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
Sebald
中科院分区：
文献类型：
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作者：
Dusold;Maisel;Sebald
研究了通过 MAS NMR 实验完全确定四 (13)C 自旋系统中 NMR 相互作用张量的大小和方向的迭代线形拟合方法的可能性和局限性。快速且数值精确的计算方法的可用性是一个重要的先决条件。本研究选择的模型化合物是马来酸单铵盐。该化合物的各种选择性和完全 (13)C 标记的版本可以逐步减少未知参数的数量，这是充分描述均匀 (13)C 标记的马来酸部分中的四 (13)C 自旋系统所必需的。这一逐步过程允许人们监测四（13）C自旋系统本身的多参数拟合的可靠性和准确性，以及表征此类拟合过程的限制和要求。 (1)令人满意的H-解耦性能是基本的实验要求； TPPM 解耦产生 n = 1, 2 旋转共振 (13)C MAS NMR 线形，适合通过迭代线形拟合方法进行分析。事实证明，关于“典型”化学屏蔽张量方向的假设，即使与真实方向偏差不大，也会导致核间距离确定中的严重错误。版权所有1999 学术出版社。
Possibilities and limitations of iterative lineshape fitting approaches for the complete determination of magnitudes and orientations of NMR interaction tensors in a four-(13)C-spin system from MAS NMR experiments are investigated. The availability of fast and numerically accurate computational methods is an important prerequisite. The model compound chosen for this investigation is the monoammonium salt of maleic acid. Various selectively and fully (13)C-labeled versions of this compound permit a stepwise reduction of the number of unknown parameters, necessary to fully describe the four-(13)C-spin system in the uniformly (13)C-labeled maleate moiety. This stepwise procedure allows one to monitor reliability and accuracy of multiparameter fits of the four-(13)C-spin system itself, as well as to characterize limitations and requirements for such fitting procedures. Satisfactory (1)H-decoupling performance is an essential experimental requirement; TPPM decoupling yields n = 1, 2 rotational resonance (13)C MAS NMR lineshapes suitable for analysis by iterative lineshape fitting methods. It is demonstrated that assumptions about "typical" chemical shielding tensor orientations, even if not deviating much from the real orientations, lead to severe errors in internuclear distance determinations. Copyright 1999 Academic Press.
慢魔角旋转核磁共振谱中的旋转边带由紧密 J 耦合的自旋对产生。
DOI：
10.1006/jmre.1996.1038
发表时间：
1997
期刊：
Journal of magnetic resonance (San Diego, Calif. : 1997)
影响因子：
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作者：
Wu,G;Sun,B;Wasylishen,RE;Griffin,RG
通讯作者：
Griffin,RG