A Practical Review of NMR Lineshapes for Spin-1/2 and Quadrupolar Nuclei in Disordered Materials

Chen, Kuizhi

doi:10.3390/ijms21165666

Cited by 26 publications

(18 citation statements)

References 78 publications

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“…Therefore, to increase the excitation bandwidth, QCPMG combined with a frequency-stepped method was used to collect individual spectra at evenly spaced transmitter offset-frequency intervals of ±166 kHz (γB 1 ). The overall 115 In NMR spectrum was then obtained by superimposing each individual spectrum. ,, On comparing the fluorine-free and fluorinated samples, it can be seen that the In local environment becomes more disordered after F – -doping, indicated by the smeared-out edges of the quadrupolar lineshape (Figure c) and the significantly broadened spectral linewidth (Figure d), which implies an increase in the quadrupolar coupling constant ( C Q ), in complete agreement with literature. ,− This result is consistent with EXAFS, MD simulation, and TEM results (vide infra).…”

Section: Results and Discussionsupporting

confidence: 86%

Fluoride Doping in Crystalline and Amorphous Indium Oxide Semiconductors

et al. 2022

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In this contribution, the structural and electronic effects of fluoride doping in both crystalline and amorphous indium oxides are investigated by both experimental and theoretical techniques. Pristine crystalline and amorphous fluoride-doped indium oxide (F:In–O) phases were prepared by solution-based combustion synthesis and sol–gel techniques, respectively. The chemical composition, environment, and solid-state microstructure of these materials were extensively studied with a wide array of state-of-the-art techniques such as UV–vis, X-ray photoelectron spectroscopy, grazing incidence X-ray diffraction, 19F and 115In solid-state NMR, high-resolution transmission electron microscopy (HR-TEM), and extended X-ray absorption fine structure (EXAFS) as well as by density functional theory (DFT) computation combined with MD simulations. Interestingly, the UV–vis data reveal that while the band gap increases upon F–-doping in the crystalline phase, it decreases in the amorphous phase. The 19F solid-state NMR data indicate that upon fluorination, the InO3F3 environment predominates in the crystalline oxide phase, whereas the InO4F2 environment is predominant in the amorphous oxide phase. The HR-TEM data indicate that fluoride doping inhibits crystallization in both crystalline and amorphous In–O phases, a result supported by the 115In solid-state NMR, EXAFS, and DFT-MD simulation data. Thus, this study establishes fluoride as a versatile anionic agent to induce disorder in both crystalline and amorphous indium oxide matrices, while modifying the electronic properties of both, but in dissimilar ways.

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Section: Results and Discussionsupporting

confidence: 86%

Fluoride Doping in Crystalline and Amorphous Indium Oxide Semiconductors

et al. 2022

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“…However, the explanations made in the first 2 paragraphs of the discussion section show that the high 1/T2 and R2-relaxivity values in question are not related to the magnetic field inhomogeneity, but due to the additional contributions caused by different relaxation mechanisms. These mechanisms should be chemical exchange between H and D, spin rotation, and the indirect involvement of quadruple relaxation [32,34,[39][40][41].The use of CDCl3 as a solvent in experiments allows different relaxation mechanisms to be involved [32]. Therefore, the high 1/T2 and R2 values obtained at the 400 MHz NMR frequency are in line with our expectations.…”

Section: Discussionsupporting

confidence: 87%

Proton $T_1$ and $T_2$ Relaxivities for $CH_2$ and $CH_3$ Peaks in Crude Oil Measured by 400 MHz NMR

Arsel

Kal

Yılmaz

2021

Journal of Engineering Technology and Applied Sciences

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Petroleum fluid has been extensively studied at low magnetic fields by Nuclear Magnetic Resonance (NMR) Spectroscopy, but high field NMR studies are rarely found in this area. The aim of this study is to determine the proton spin-lattice relaxation rate (1/T 1 ), T 1 relaxivity (R 1 ), proton spin-spin relaxation rate (1/T 2 ) and T 2 relaxivity (R 2 ) of paraffinic CH 2 and gamma CH 3 peaks. For this purpose, crude oil samples were taken from 3 separate wells in the Batman region. Using these samples, 3 different sets were prepared from a mixture of deuterated chloroform (CDCl 3 ) and crude oil. The total volume of each prepared mixture was 1 mL. The crude oil content in each set was changed from 0.05 mL to 0.20 mL in 0.05 mL steps.. Special care has been taken to ensure the best shimming of the NMR spectrometer operating at 400 MHz. T 1 measurements were performed using an inversion recovery (IR) pulse sequence. 1/T 2 values were determined from the half-height line widths of CH 2 and CH 3 peaks. 1/T 1 and 1/T 2 rates and all relaxivities were found to vary from well to well. This change is due to the fluid composition of the wells. The 1/T 2 rates and R 2 relaxivities were found to be considerably greater than the 1/T 1 rates and R 1 relaxivities. R 2 relaxivities for CH 3 were also 2-5 times greater than for CH 2 .The higher 1/T 2 and R 2 relaxivities compared with 1/T 1 and R 1 were attributed to the additional CDCl 3mediated relaxation mechanisms. In conclusion, available data show that high 1/T 2 rates and R 2 relaxivities measured in the high field NMR laboratory can be applied to separate crude oil from other fluids in the oil field.

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“…As shown in the 27 Al MQMAS spectrum for TMP-treated C-ZSM-5 in Figure a, three main signals are clearly separated, denoted Al IV,a , Al IV,b , and Al V , which are marked in blue, red, and green, respectively. The green signal centers at (33, 40) and can be assigned to penta-coordinated Al species (Al V ) due to its characteristic 27 Al chemical shift around the 30–40 ppm region. , The blue and red signals correspond to tetrahedrally coordinated Al species Al IV,a and Al IV,b , possessing small and large C Q values, respectively, indicated by the narrow and broad/horizontal patterns along the F 2 dimension as has been demonstrated clearly in the literature. , It should be noted that although the chemical shift of Al IV,b in the indirect dimension appears at ca. 70 ppm, its actual δ iso is around 59 ppm (but clearly with chemical shift/quadrupolar shift distributions due to the broad spectral pattern) as shown in a typical analysis of quadrupolar parameters in Figure S5, indicating that the aluminum in the TMP-Lewis acid adduct is tetrahedrally coordinated, which accounts for the assignment of this species as Al IV .…”

Section: Resultsmentioning

confidence: 64%

Identity, Evolution, and Acidity of Partially Framework-Coordinated Al Species in Zeolites Probed by TMP ³¹P-NMR and FTIR

et al. 2023

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Increasing research has shown that active sites in zeolite catalysts are structurally and spatially complex, which poses challenges to effective characterization methods, especially for the high demand in pursuing molecular-level understanding of the nature of the active sites. Herein, using trimethylphosphine (TMP) as a probe molecule, the species giving rise to 31 P NMR resonance at −58 ppm, which is typically recognized as TMP physically adsorbed on unreactive species, is found to possess more catalytic meanings as the TMP bindings are proven to be strong. NMR-assisted 31 P-27 Al internuclear distance measurement and a comprehensive set of two-dimensional (2D) heteronuclear correlation (HETCOR) ( 1 H-31 P, 31 P-27 Al, and 27 Al-1 H) NMR experiments explicitly demonstrate that the TMP-binding site is neither a bridging acid site (BAS) nor a Lewis acid site (LAS), but special Al−OH groups, i.e., Al−OH•••P(CH 3 ) 3 . Further evidence including postsynthetic treatments and 31 P-31 P homonuclear NMR correlation experiments exclusively shows that these Al−OH groups originate from the partially bonded framework Al(IV)-2 species recently reported. By linking IR and 1 H NMR spectroscopy, new insights of Al(IV)-2 (essentially Brønsted sites) and framework-bonded Lewis sites are provided. Finally, 31 P-31 P homonuclear correlation experiment was capable of ruling out chemical exchange from spin diffusion and thereby exclusively demonstrates that the "BAS and Al(IV)-2" is in shorter spatial distance than that of "BAS and LAS".

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A Practical Review of NMR Lineshapes for Spin-1/2 and Quadrupolar Nuclei in Disordered Materials

Cited by 26 publications

References 78 publications

Fluoride Doping in Crystalline and Amorphous Indium Oxide Semiconductors

Fluoride Doping in Crystalline and Amorphous Indium Oxide Semiconductors

Proton $T_1$ and $T_2$ Relaxivities for $CH_2$ and $CH_3$ Peaks in Crude Oil Measured by 400 MHz NMR

Identity, Evolution, and Acidity of Partially Framework-Coordinated Al Species in Zeolites Probed by TMP ³¹P-NMR and FTIR

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A Practical Review of NMR Lineshapes for Spin-1/2 and Quadrupolar Nuclei in Disordered Materials

Cited by 26 publications

References 78 publications

Fluoride Doping in Crystalline and Amorphous Indium Oxide Semiconductors

Fluoride Doping in Crystalline and Amorphous Indium Oxide Semiconductors

Proton $T_1$ and $T_2$ Relaxivities for $CH_2$ and $CH_3$ Peaks in Crude Oil Measured by 400 MHz NMR

Identity, Evolution, and Acidity of Partially Framework-Coordinated Al Species in Zeolites Probed by TMP 31P-NMR and FTIR

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Product

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Identity, Evolution, and Acidity of Partially Framework-Coordinated Al Species in Zeolites Probed by TMP ³¹P-NMR and FTIR