Millot Yannick, Man Pascal P
Systèmes Interfaciaux a l'Echelle Nanométrique, CNRS FRE 2312, Laboratoire de Chimie des Surfaces, Université Pierre et Marie Curie, Paris, France.
Solid State Nucl Magn Reson. 2002 Feb-Mar;21(1-2):21-43. doi: 10.1006/snmr.2001.0043.
The increasing development and application of the multiple-quantum MAS NMR for half-integer quadrupole spins has led to various RF pulse sequences for improving the excitation of multiple-quantum coherences and their conversion to single-quantum coherences. As a result, several conventions for labeling the Fl dimension of a 2D MQ-MAS spectrum appear in the literature. The corresponding relations for extracting the isotropic chemical shift, the quadrupole coupling constant, and the asymmetry parameter from experimental data are not always provided. We analyze these various conventions systematically and propose a new one, similar to that introduced by J.-P. Amoureux and C. Fernandez (2000, Solid State NMR 10, 339-343). These various conventions are illustrated with 27Al (I = 5/2) nuclei in aluminum acetylacetonate Al(CH3COCHCOCH3)3. Another experimental problem often met, the aliasing of peaks in the 2D spectrum, is analyzed and illustrated with 27Al (I = 5/2) in NH4Y zeolite and 23Na (I = 3/2) in sodium pyrophosphate Na4P2O7.
用于半整数四极自旋的多量子MAS NMR技术的不断发展和应用，催生了各种射频脉冲序列，以改善多量子相干的激发及其向单量子相干的转换。因此，文献中出现了几种标记二维MQ-MAS谱F1维度的约定。但从实验数据中提取各向同性化学位移、四极耦合常数和不对称参数的相应关系却并非总能提供。我们系统地分析了这些不同的约定，并提出了一种新的约定，类似于J.-P. 阿穆鲁克斯和C. 费尔南德斯（2000年，《固态核磁共振》10，339 - 343）所介绍的那种。通过乙酰丙酮铝Al(CH3COCHCOCH3)3中的27Al（I = 5/2）核来说明这些不同的约定。另一个经常遇到的实验问题，即二维谱中的峰混叠，通过NH4Y沸石中的27Al（I = 5/2）和焦磷酸钠Na4P2O7中的23Na（I = 3/2）进行了分析和说明。
