Solid-state CP/MAS 13C NMR analysis of particle size and density fractions of a soil incubated with uniformly labeled 13C-glucose

Soil Research ◽  
1990 ◽  
Vol 28 (2) ◽  
pp. 193 ◽  
Author(s):  
JA Baldock ◽  
JM Oades ◽  
AM Vassallo ◽  
MA Wilson
Keyword(s):  
Solid State ◽  
Relaxation Times ◽  
Clay Fraction ◽  
Lattice Relaxation ◽  
Magic Angle Spinning ◽  
Spin Lattice Relaxation ◽  
Resonance Spectroscopy ◽  
Magic Angle ◽  
Ultrasonic Probe ◽  
13C Nuclear Magnetic Resonance

A soil incubated for 34 days in the absence (control) and presence (treated) of uniformly labelled 13C-glucose was dispersed using an ultrasonic probe and fractionated by sedimentation in water and a polytungstate solution of density 2.0 Mg m3 . The residual substrate carbon was concentrated in the clay and light fractions. Solid state CP/MAS 13C n.m.r. (cross polarization/magic angle spinning 13c nuclear magnetic resonance) spectroscopy was used to characterize the chemical structure of the native soil organic carbon and the residual substrate carbon in the fractions of the control and treated soils. To obtain quantitative results it was essential to determine the spin lattice relaxation times in the rotating frame, T1pH, of the individual carbon types in the spectra as the relaxation behaviour of the native organic materials in the clay fraction was substantially different from that of the residual substrate carbon. After correcting for T1pH effects, a significant linear relationship existed between the signal intensity and 13C content of the samples. This enabled the content, expressed in �mol 13C g-1 fraction, of each type of carbon in the fractions to be calculated. The residual substrate carbon was found to accumulate in predominantly alkyl and O-alkyl structures in both fractions. However, significant amounts of acetal and carboxyl carbon were also observed in the clay fraction. Little if any aromatic or phenolic carbon was synthesized by the soil microorganisms utilizing substrate carbon. Dipolar dephasing CP/MAS 13C n.m.r. experiments were also performed and allowed the proportion of each type of carbon which was protonated and nonprotonated to be estimated. Essentially all of the O-alkyl and acetal carbon, 25-40% of the aromatic carbon and 66-80% of the alkyl carbon was protonated in the fractions isolated from the treated soil

Phosphorus-31 and vanadium-51 solid-state nuclear magnetic resonance spectroscopy of β-vanadyl phosphate — Effects of homo- and heteronuclear spin-spin, electrostatic, and paramagnetic interactions

2011 ◽  
Vol 89 (7) ◽  
pp. 870-884 ◽  
Author(s):  
Klaus Eichele ◽  
Arnd-Rüdiger Grimmer
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Chemical Shift Anisotropy ◽  
Lattice Relaxation ◽  
Nuclear Quadrupole Interaction ◽  
Magic Angle Spinning ◽  
Spin Lattice Relaxation ◽  
Resonance Spectroscopy ◽  
Magic Angle ◽  
Nmr Studies

Field-dependent 31P solid-state NMR studies demonstrate that the line shape in spectra of β-VOPO4 depends on 51V–31P direct and indirect spin-spin interactions (M2 (51V, 31P) = 101(23) × 106 rad2 s–2, 2Jiso (51V, 31P) = 48(5) Hz) and, to a lesser extent, on 31P chemical shift anisotropy (δiso = –10.4(2), Ω = δ11 – δ33 = 22(2) ppm) and 31P–31P interactions (M2 (31P, 31P) = 6.7(1) × 106 rad2 s–2). In contrast, homonuclear dipolar interactions play an important role for the field and spinning rate dependent 31P spin-lattice relaxation via paramagnetic impurities (T1 = 20–60 s). Vanadium-51 magic-angle spinning NMR spectra indicate a sizeable chemical shift anisotropy (δiso = –754(1), δ11 = –336(10), δ22 = –344(6), δ33 = –1581(8) ppm) and nuclear quadrupole interaction (χ = 1.5(1) MHz, η = 0.35(5)); the principal axis systems of both interactions are clearly not coincident, with an angle of 35(5)° between the greatest component of the electric field gradient tensor and δ33.

scholarly journals Physicochemical properties and structural dynamics of organic–inorganic hybrid [NH3(CH2)3NH3]ZnX4 (X = Cl and Br) crystals

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ae Ran Lim ◽  
Sun Ha Kim ◽  
Yong Lak Joo
Keyword(s):  
Structural Dynamics ◽  
Chemical Shifts ◽  
Lattice Relaxation ◽  
Magic Angle Spinning ◽  
Spin Lattice Relaxation ◽  
Resonance Spectroscopy ◽  
Magic Angle ◽  
Scanning Calorimetry ◽  
Inorganic Hybrid ◽  
Halogen Atoms

AbstractThe physical properties of the organic–inorganic hybrid crystals having the formula [NH3(CH2)3NH3]ZnX4 (X = Cl, Br) were investigated. The phase transition temperatures (TC; 268K for Cl and 272K for Br) of the two crystals bearing different halogen atoms in their skeletons were determined through differential scanning calorimetry. The thermodynamic properties of the two crystals were investigated through thermogravimetric analysis. The structural dynamics, particularly the role of the [NH3(CH2)3NH3] cation, were probed through 1H and 13C magic-angle spinning nuclear magnetic resonance spectroscopy as a function of temperature. The 1H and 13C NMR chemical shifts did not show any changes near TC. In addition, the 1H spin–lattice relaxation time (T1ρ) varied with temperature, whereas the 13C T1ρ values remained nearly constant at different temperatures. The T1ρ values of the atoms in [NH3(CH2)3NH3]ZnCl4 were higher than those in [NH3(CH2)3NH3]ZnBr4. The observed differences in the structural dynamics obtained from the chemical shifts and T1ρ values of the two compounds can be attributed to the differences in the bond lengths and halogen atoms. These findings can provide important insights or potential applications of these crystals.

Application of High-Resolution-Magic-Angle-Spinning (HR-MAS) NMR Spectroscopy to Cosmetic Emulsions

2000 ◽  
Vol 55 (7) ◽  
pp. 651-656 ◽  
Author(s):  
Li-Hong Tseng ◽  
Detlef Emeis ◽  
Martin Raitza ◽  
Heidrun Händel ◽  
Klaus Albert
Keyword(s):  
Nmr Spectroscopy ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
2D Nmr ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Phase Changes ◽  
Spin Lattice Relaxation ◽  
Magic Angle ◽  
Angle Spinning

Abstract HR-MAS NMR spectroscopy was utilized for the characterization of three cosmetic emul­sions. The emulsions had the same chemical composition and were prepared in the same way except the homogenization step. Magic angle spinning (M A S) of the emulsions was applied to improve signal resolution by eliminating susceptibility changes as well as residual dipolar interactions within the sample. Spin-lattice relaxation times (T1) were determined according to the inversion recovery technique in the temperature range of -10 °C to 40 °C to find out phase changes of the sample ingredients. 1H and 13C NMR signals of the individual components were assigned by use of different 1D and 2D NMR experiments. The HR-MAS NMR technique offers many possibilities to further investigate samples between the liquid and the solid state.

1H-Detected quadrupolar spin–lattice relaxation measurements under magic-angle spinning solid-state NMR

2019 ◽  
Vol 55 (39) ◽  
pp. 5643-5646 ◽  
Author(s):  
Maria Makrinich ◽  
Amir Goldbourt
Keyword(s):  
Solid State Nmr ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Magic Angle Spinning ◽  
Spin Lattice Relaxation ◽  
Magic Angle ◽  
Proton Detection ◽  
Spin Lattice ◽  
Relaxation Measurements ◽  
Angle Spinning

Proton detection and phase-modulated pulse saturation enable the measurement of spin–lattice relaxation times of “invisible” quadrupolar nuclei with extensively large quadrupolar couplings.

scholarly journals Exploring the Role of Phosphate Structural Distortions on the Sodium Jump Dynamics in NASICON Phases

2015 ◽  
Vol 1773 ◽  
pp. 1-6
Author(s):  
Todd M. Alam ◽  
Nelson Bell ◽  
Jill Wheeler ◽  
Erik D. Spoerke ◽  
Randall T. Cygan ◽  
...  
Keyword(s):  
Sol Gel ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Magic Angle Spinning ◽  
Spin Lattice Relaxation ◽  
Magic Angle ◽  
Spin Lattice ◽  
Relaxation Experiments ◽  
Jump Dynamics ◽  
Angle Spinning

ABSTRACTHigh temperature solid state sodium (23Na) magic angle spinning (MAS) NMR spin lattice relaxation times (T1) were evaluated for a series of NASICON (Na3Zr2PSi2O12) materials to directly determine Na jump rates. Simulations of the T1 temperature variations that incorporated distributions in Na jump activation energies, or distribution of jump rates, improved the agreement with experiment. The 23Na NMR T1 relaxation results revealed that distributions in the Na dynamics were present for all of the NASICON materials investigated here. The 23Na relaxation experiments also showed that small differences in material composition and/or changes in the processing conditions impacted the distributions in the Na dynamics. The extent of the distribution was related to the presence of a disordered or glassy phosphate phase present in these different sol-gel processed materials. The 23Na NMR T1 relaxation experiments are a powerful tool to directly probing Na jump dynamics and provide additional molecular level details that could impact transport phenomena.

Tin-119 NMR of 1,3,2-dioxastannolanes and a 1,3,2-dioxastannane in the solid state

1992 ◽  
Vol 70 (1) ◽  
pp. 205-217 ◽  
Author(s):  
T. Bruce Grindley ◽  
Roderick E. Wasylishen ◽  
Rasiah Thangarasa ◽  
William P. Power ◽  
Ronald D. Curtis
Keyword(s):  
Solid State ◽  
High Resolution ◽  
Chemical Shift ◽  
Variable Temperature ◽  
Lattice Relaxation ◽  
Magic Angle Spinning ◽  
Spin Lattice Relaxation ◽  
Magic Angle ◽  
X Ray ◽  
Spin Lattice

The cross-polarized static and high-resolution magic angle spinning 119Sn NMR spectra of a number of 2,2-dialkyl-1,3,2-dioxastannolanes and one 1,3,2-dioxastannane have been measured in the solid state. For the four compounds on which X-ray studies had been performed, the numbers and positions of the isotropic peaks in the high-resolution spectra were related to the number of tin sites present and the state of oligomerization of the compounds. The chemical shifts of hexacoordinate Sn nuclei are 35–80 ppm larger in polymeric solids than for the same compounds in solution where the compounds exist as trimers and tetramers. States of oligomerization for solids that had not been previously studied by X-ray crystallography were determined using CP/MAS 119Sn NMR spectroscopy. The principal components of the 119Sn chemical shift tensors were obtained from the static spectra and used to calculate chemical shift anisotropies and asymmetry parameters. The values of the chemical shift anisotropies ranged from 600 to 800 ppm for 1,3,2-dioxastannolanes but the value for a 1,3,2-dioxastannane was larger, 919 ppm. The chemical shift anisotropies measured directly from the solid-state powder patterns are in excellent agreement with the values derived from previous variable temperature spin-lattice relaxation measurements in solution when the same oligomer was present in both states. Our results support our previous conclusion that the antisymmetric terms of the chemical shift tensor make a small or negligible contribution to the rate of 119Sn spin-lattice relaxation in these compounds. Keywords: 1,3,2-dioxastannolanes, stannylene acetals, 119Sn NMR, 119Sn NMR of solids, 119Sn chemical shift an-isotropy.

High resolution 13C nuclear magnetic resonance spectra of solid pyrazoles. Application to annular tautomerism

1988 ◽  
Vol 66 (5) ◽  
pp. 1141-1146 ◽  
Author(s):  
Robert Faure ◽  
Émile-Jean Vincent ◽  
André Rousseau ◽  
Rose Maria Claramunt ◽  
José Elguero
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Solid State ◽  
Magnetic Resonance ◽  
Magic Angle Spinning ◽  
Resonance Spectroscopy ◽  
Magic Angle ◽  
13C Nuclear Magnetic Resonance ◽  
Annular Tautomerism ◽  
Angle Spinning ◽  
Nuclear Magnetic

Carbon-13 nuclear magnetic resonance spectroscopy in the solid state (cross polarization/magic angle spinning technique) is a very suitable method for studying the annular tautomerism of pyrazoles. In all the compounds studied, the tautomerism is frozen and the signals are well resolved except for 3,5-dimethyl-4-nitro pyrazole, which shows broad signals. In the case of 4-substituted derivatives of 3(5)-methylpyrazoles, the tautomer present in the solid state is a 4-X-5 methylpyrazole. 3-Phenyl-5-methylpyrazole (4H or 4-methyl) is favoured over the 3-methyl-5-phenyl tautomer.

Pulse Shaped Dynamic Nuclear Polarization Under Magic Angle Spinning

2019 ◽  
Author(s):  
ASIF EQUBAL ◽  
Kan Tagami ◽  
Songi Han
Keyword(s):  
Electron Spin ◽  
Lattice Relaxation ◽  
Magic Angle Spinning ◽  
Spin Lattice Relaxation ◽  
Magic Angle ◽  
Total Electron ◽  
Spin Lattice ◽  
Maximum Benefit ◽  
Selective Saturation ◽  
Angle Spinning

In this paper, we report on an entirely novel way of improving the MAS-DNP efficiency by shaped μw pulse train irradiation for fast and broad-banded (FAB) saturation of the electron spin resonance. FAB-DNP achieved with Arbitrary Wave Generated shaped μw pulse trains facilitates effective and selective saturation of a defined fraction of the total electron spins, and provides superior control over the DNP efficiency under MAS. Experimental and quantum-mechanics based numerically simulated results together demonstrate that FAB-DNP significantly outperforms CW-DNP when the EPR-line of PAs is broadened by conformational distribution and exchange coupling. We demonstrate that the maximum benefit of FAB DNP is achieved when the electron spin-lattice relaxation is fast relative to the MAS frequency, i.e. at higher temperatures and/or when employing metals as PAs. Calculations predict that under short T<sub>1e </sub>conditions AWG-DNP can achieve as much as ~4-fold greater enhancement compared to CW-DNP.

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