Observation of spinning sidebands in the 27Al magic-angle spinning nuclear magnetic resonance spectra of FAU and EMT structure-type zeolites

Characterization of Aluminosilicates in Fly Ashes with Different Melting Points Using 27Al Magic-Angel Spinning Nuclear Magnetic Resonance

“…When a MAS NMR spectrum is recorded, spinning sidebands are generated because the MAS speed/frequency is lower than the intensity/frequency of the inhomogeneous anisotropic interactions of the observed nucleus at a certain atom site in substances. The anisotropic interactions of half-integer quadrupolar nuclei consist mainly of quadrupolar interaction and anisotropic chemical shielding. ,, 27 Al nuclei hold a spin of 5/2. The quadrupolar interaction can reach the order of MHz, whereas the chemical shielding anisotropy is generally much weaker than the quadrupolar interaction. , The more distorted the electric field gradient tensor at the 27 Al nucleus, the stronger the generation of the quadrupole effect and spinning sidebands.…”

“…The anisotropic interactions of half-integer quadrupolar nuclei consist mainly of quadrupolar interaction and anisotropic chemical shielding. ,, 27 Al nuclei hold a spin of 5/2. The quadrupolar interaction can reach the order of MHz, whereas the chemical shielding anisotropy is generally much weaker than the quadrupolar interaction. , The more distorted the electric field gradient tensor at the 27 Al nucleus, the stronger the generation of the quadrupole effect and spinning sidebands. In this study, the MAS speed for all the samples is 12 kHz.…”

“…In this article, we conducted hydrochloric acid separations for fly ashes with different melting points obtained from four power plants in China and measured the solubility of the major elements in the fly ashes. XRD and 27 Al magic-angle spinning nuclear magnetic resonance ( 27 Al MAS NMR) are employed to analyze the fly ash samples before and after acid separation. The aluminum coordination characteristics of the fly ashes with different melting points are studied.…”

“…12,13 When the NMR spectra of solid powder samples are collected, the MAS technique is capable of eliminating the anisotropic contributions of chemical shift anisotropy and dipolar interaction to the spectra. However, 27 Al is a halfinteger quadrupolar nucleus with a spin of 5/2 and possesses an electric quadrupolar moment. Its interaction with inhomogeneous electric fields is called quadrupolar interaction, which has an important effect on 27 Al NMR.…”

“…However, 27 Al is a halfinteger quadrupolar nucleus with a spin of 5/2 and possesses an electric quadrupolar moment. Its interaction with inhomogeneous electric fields is called quadrupolar interaction, which has an important effect on 27 Al NMR. MAS can only partially average the second-order quadrupolar interaction of 27 Al.…”