14N and 39K Nuclear Quadrupole Coupüng in KNO3

Bastow, T. J.; Stuart, S. N.

doi:10.1515/zna-1990-3-442

Cited by 14 publications

(4 citation statements)

References 11 publications

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“…The parameters obtained through the computer optimization are C Q = 746 ± 10 kHz, η Q = 0.02 ± 0.01, δ iso = 342.7 ± 0.1 ppm (relative to solid NH 4 Cl), and a deviation of the rotor angle of −0.009° from the exact magic angle. These data are in excellent agreement with the quadrupole coupling parameters determined from single-crystal 14 N NMR spectroscopy (see Table ) . The simulation in Figure b includes fixed parameters for the 14 N CSA (δ σ = 145 ppm and η σ = 0.11), determined as the 15 N CSA from 15 N MAS spectra of KNO 3 (95% 15 N-enriched from Cambridge Isotope Laboratories) at 14.1 T. These data are in good agreement with the values obtained from a single-crystal 14 N NMR study of KNO 3 (δ σ = 149.8 ppm and η = 0.010) .…”

supporting

confidence: 82%

¹⁴N MAS NMR Spectroscopy: The Nitrate Ion

et al. 2001

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Great efforts have been exercised during the past few years in applying magic-angle spinning (MAS) NMR spectroscopy to the highly abundant 14 N quadrupolar nucleus (99.6% natural abundance, spin I ) 1) in polycrystalline solids. [1][2][3] Obviously a successful outcome of these efforts would be highly appreciated in particular if the resulting spinning sideband (ssb) spectra would be of sufficient quality to allow analysis in a straightforward manner, thereby yielding useful spectral parameters. For example, this could involve the procedures and versatile software programs already developed for the analyses of spinning sideband spectra (the complete manifold and/or individual ssb line shapes) for halfinteger spin (I ) 3 / 2 , 5 / 2 , 7 / 2 , ...) quadrupolar nuclei and 2 H. [4][5][6][7][8][9][10] The potential of a routine determination for the 14 N quadrupole coupling constant (C Q ) and asymmetry parameter (η Q ) from such spectra would constitute a valuable parameter set characterizing the environment of the nitrogen atom in addition to the isotropic/ anisotropic 15 N chemical shift data, oftentimes determined using 15

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confidence: 82%

¹⁴N MAS NMR Spectroscopy: The Nitrate Ion

et al. 2001

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“…Until very recently, 39 K NMR has seen very few applications in the solid state because of difficulties in obtaining spectra, as both isotopes, 39 K and 41 K (natural abundance of 93.7 and 6.3%, respectively), are spin- 3 / 2 quadrupolar nuclei with low magnetogyric ratios (absolute resonance frequencies of Ξ = 4.6664 MHz for 39 K and Ξ = 2.5613 MHz for 41 K). The total number of publications involving the more easily observed 39 K nucleus is relatively small and involves results on potassium halides (cubic lattice = zero quadrupole interactions), several studies of single crystals, − and powders. − Most of the studies were performed in magnetic fields of intermediate strengths of 7−11 T, with a single study reporting 39 K NMR in some minerals at 21 T . Two recent high-field studies (19.6 T) were devoted to examination of potassium tetraphenylborates and the detection of potassium cations bound to G-quadruplex structures found in telomeric DNA…”

Section: Introductionmentioning

confidence: 99%

³⁹K NMR of Solid Potassium Salts at 21 T: Effect of Quadrupolar and Chemical Shift Tensors

Moudrakovski

Ripmeester

2007

J. Phys. Chem. B

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39K Solid State NMR spectra (static and magic angle spinning (MAS)) on a set of potassium salts measured at 21.14 T show that the chemical shift range for K(+) ions in diamagnetic salts is well in excess of 100 ppm contrary to previous assumptions that it was quite small. Inequivalent potassium sites in crystals can be resolved through differences in chemical shifts, with chemically similar sites showing differences of over 10 ppm. The quadrupolar coupling constants obtained from MAS and solid echo experiments on powders cover the range from zero for potassium in cubic environments in halides to over 3 MHz for the highly asymmetric sites in K2CO3. Although the quadrupolar effects generally dominate the 39K spectra, in several instances, we have observed subtle but significant contributions of chemical shift anisotropy with values up to 45 ppm, a first such observation. Careful analysis of static and MAS spectra allows the observation of the various chemical shift and quadrupole coupling tensor components as well as their relative orientations, thereby demonstrating that high-field 39K NMR spectroscopy in the solid state has a substantial sensitivity to the local environment with parameters that will be of considerable value in materials characterization and electronic structure studies.

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“…Another consequence of the low VL is that acoustic ringing and other low frequency artefacts are often present, so that undistorted NMR powder lineshapes are difficult to obtain. Indeed, very few authors have reported 39K solid-state NMR results to date and these have mostly been on simple model compounds (Kunwar et al, 1986;Bastow and Stuart, 1990 and references therein).…”

Section: Introductionmentioning

confidence: 99%

³⁹K Solid-State NMR Studies of Potassium Tecto- and Phyllosilicates: The In Situ Detection of Hydratable K⁺ in Smectites

Lambert

1992

Clays and clay miner.

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Abstract--We report the first application of 39K solid-state NMR to the study of tecto-and phyllosilicates. Under high field (11.7 Tesla) and with the application of a spin-echo sequence, informative 39K spectra can be obtained for several compounds of interest to the geologist and the agronomist. Tectosilicates and phyllosilicates can be distinguished from the uncorrected frequency (Sc6) of the observed NMR peak. A series of montmorillonites submitted to increasing numbers of wetting and drying cycles was studied in order to discriminate between mobile and "fixed" forms of K+: when the spectra are run on hydrated samples, two different signals are observed corresponding to K § in different hydration states, and NMR data can be correlated with the amount of exchangeable K + measured by ion exchange. Thus, it appears that NMR can provide useful information on K fixation complementary to classical chemical methods.

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¹⁴N and ³⁹K Nuclear Quadrupole Coupüng in KNO₃

Cited by 14 publications

References 11 publications

¹⁴N MAS NMR Spectroscopy: The Nitrate Ion

¹⁴N MAS NMR Spectroscopy: The Nitrate Ion

³⁹K NMR of Solid Potassium Salts at 21 T: Effect of Quadrupolar and Chemical Shift Tensors

³⁹K Solid-State NMR Studies of Potassium Tecto- and Phyllosilicates: The In Situ Detection of Hydratable K⁺ in Smectites

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14N and 39K Nuclear Quadrupole Coupüng in KNO3

Cited by 14 publications

References 11 publications

14N MAS NMR Spectroscopy: The Nitrate Ion

14N MAS NMR Spectroscopy: The Nitrate Ion

39K NMR of Solid Potassium Salts at 21 T: Effect of Quadrupolar and Chemical Shift Tensors

39K Solid-State NMR Studies of Potassium Tecto- and Phyllosilicates: The In Situ Detection of Hydratable K+ in Smectites

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¹⁴N and ³⁹K Nuclear Quadrupole Coupüng in KNO₃

¹⁴N MAS NMR Spectroscopy: The Nitrate Ion

¹⁴N MAS NMR Spectroscopy: The Nitrate Ion

³⁹K NMR of Solid Potassium Salts at 21 T: Effect of Quadrupolar and Chemical Shift Tensors

³⁹K Solid-State NMR Studies of Potassium Tecto- and Phyllosilicates: The In Situ Detection of Hydratable K⁺ in Smectites