Variable-Temperature High-Resolution Proton NMR Study of Laboratory-Frame and Rotating-Frame Spin−Lattice Relaxation in Coals

1997 ◽  
Vol 11 (4) ◽  
pp. 866-878 ◽  
Author(s):  
Jincheng Xiong ◽  
Gary E. Maciel
Keyword(s):  
High Resolution ◽  
Variable Temperature ◽  
Proton Nmr ◽  
Lattice Relaxation ◽  
Laboratory Frame ◽  
Spin Lattice Relaxation ◽  
Rotating Frame ◽  
Spin Lattice ◽  
Nmr Study

scholarly journals NMR relaxometry: Spin lattice relaxation times in the laboratory frame versus spin lattice relaxation times in the rotating frame

2010 ◽  
Vol 495 (4-6) ◽  
pp. 287-291 ◽  
Author(s):  
Emilie Steiner ◽  
Mehdi Yemloul ◽  
Laouès Guendouz ◽  
Sébastien Leclerc ◽  
Anthony Robert ◽  
...  
Keyword(s):  
Relaxation Times ◽  
Lattice Relaxation ◽  
Laboratory Frame ◽  
Spin Lattice Relaxation ◽  
Rotating Frame ◽  
Spin Lattice ◽  
Nmr Relaxometry

NMR Study of Cation Motions in Ferroic [C(NH2)3]3Bi2Br9

2000 ◽  
Vol 55 (6-7) ◽  
pp. 570-574 ◽  
Author(s):  
M. Grottel ◽  
Z. Paja̡ka ◽  
R. Jakubasb
Keyword(s):  
Relaxation Time ◽  
Phase Transitions ◽  
Wide Temperature Range ◽  
Proton Nmr ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Potential Barriers ◽  
Spin Lattice ◽  
Nmr Study

The proton NMR second moment and spin-lattice relaxation time of polycrystalline [C(NH2)3]3Bi2Br9 were studied in a wide-temperature range. Dynamical inequivalence of two crystallographically different guanidinium cations has been revealed . The C3 reorientation of the two types of cations was found to be hindered by different potential barriers (25.1 kJ/mol and 34.7 kJ/mol). At higher temperatures an overall reorientation of the cations was revealed. The existence and order-disorder character of the phase transitions at 333, 350, 415, and 425 K have been confirmed.

Molecular Dynamics in the Solid Trimethylamine-Borane Complex: A Deuterium NMR Study

1995 ◽  
Vol 50 (1) ◽  
pp. 81-89 ◽  
Author(s):  
Glenn H. Penner ◽  
Baiyi Zhao ◽  
Kenneth R. Jeffrey
Keyword(s):  
Molecular Dynamics ◽  
Variable Temperature ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Activation Energies ◽  
Spin Lattice Relaxation ◽  
Deuterium Nmr ◽  
Molecular Orbital Calculations ◽  
Spin Lattice ◽  
Nmr Study

Abstract The molecular dynamics of solid (CH3)3NBH3 is investigated by deuterium NMR spectroscopy. Variable temperature lineshape analyses yield activation energies of 27 ± 3, 19 ± 2, and 12.5 ± 2 kJ/mol for -CH3, -N(CH3)3 and -BH3 rotation, respectively. Analysis of the temperature depen­ dence of the spin-lattice relaxation times, T1 , gives activation energies of 33 ± 3, 15 ± 1.5, and 14 ± 1.5 kJ/mol, respectively. Direct comparison of rotational exchange rates (from lineshape simu­ lations) an of rotational correlation times (from T1 analyses) for -N(CH3)3 and -BH3 rotation indicate that the two motions are correlated in solid (CH3)3NBH3 and together constitute a whole molecule reorientation about the N-B bond. This is supported by an internal rotational barrier of 18.0 kJ/mol for-BH3 rotation, obtained from ab initio molecular orbital calculations at the MP2/6-31G* level.

SOLID STATE NMR STUDY ON MICROBIAL POLY(ε-L-LYSINE)/CARBOXYMETHYL CELLULOSE BLENDS

2011 ◽  
Vol 25 (31) ◽  
pp. 4315-4318
Author(s):  
SHIRO MAEDA ◽  
KUMIKO KATO ◽  
KEN TAKAGI ◽  
MINA KOBAYASHI ◽  
KO-KI KUNIMOTO
Keyword(s):  
Solid State ◽  
Carboxymethyl Cellulose ◽  
Lattice Relaxation ◽  
Laboratory Frame ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Carbon Dioxide Gas ◽  
Nmr Study ◽  
Carboxymethyl Cellulose Sodium

The miscibility of microbial poly(ε- L -lysine)/carboxymethyl cellulose sodium salt (ε-PL/CMC) blends was investigated by solid-state nuclear magnetic resonance methods. 1 H spin-lattice relaxation time in the laboratory frame T1, and in the rotating frame, T1ρ measurements indicate that the blends are miscible at all compositions on a scale of 2–5 nm. Formation of carbamates and its reversibility were examined. ε-PL/CMC hydrogel was formed by bubbling carbon dioxide gas into ε-PL and CMC aqueous solution mixture.

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.

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