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经~(23)Na魔角旋转(MAS)及二维四极章动(two dimensional quadrupolar nutation)核磁共振(NMR)表征:水合Omega分子筛中Na~+至少有两种不同局域环境,分别对应NMR谱中的低场和高场信号.在分子筛中,对于半整数四极核(如~(23)Na,自旋量子数I=3/2),除二阶四极作用外,化学位移作用也往往是核所处局域环境的重要表征,而MAS NMR方法为窄化谱线,消除了化学位移各向异性作用,从而也就失去了这部分有关信息.变角样品旋转(VASS)
Characterization by ~ (23) Na Magic Quadrature Rotation (MAS) and Two Dimensional Quadrupolar Nutation NMR: There are at least two different kinds of Na + in the hydrated Omega molecular sieve, corresponding to NMR spectra of the low-field and high-field signals.In the molecular sieve, for the semi-integer quadrupole nucleus (such as ~ (23) Na, the spin quantum number I = 3/2), in addition to the second- Displacement is also often an important characterization of the local environment in which the nuclei are located, whereas the MAS NMR method narrows the spectrum and eliminates the chemical shift anisotropy, thus losing some of this information.Variable Sample Rotation (VASS )