Anisotropic relaxation and motion of half-integer quadrupole nuclei studied by central transition nuclear magnetic resonance spectroscopy

Kristensen, J.H.; Farnan, Ian

doi:10.1016/s1090-7807(02)00065-4

Cited by 15 publications

(9 citation statements)

References 39 publications

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“…In order to explain the Cs lineshapes obtained as a function of temperature, computer simulations were carried out, using a formalism and code previously developed within our group, 25 to study the effects of motion on the spectra of quadrupolar nuclei for both central and satellite transitions. Further details on the implementation of the calculation can be found in Kristensen and Farnan 25 . The main input parameters for calculations include the spin quantum number, Larmor frequency, and a definition of the exchanging sites.…”

Section: Resultsmentioning

confidence: 99%

“…Further details on the implementation of the calculation can be found in Kristensen and Farnan. 25 The main input parameters for calculations include the spin quantum number, Larmor frequency, and a definition of the exchanging sites. More precisely, we define the number of sites, their populations, their relative orientations (Euler angles from the first site to the nth site), the chemical shift (CSA) and quadrupolar interaction tensors on each site, and an exchange matrix including the hopping rates n k (l, m) from the lth site to the mth site.…”

Section: Resultsmentioning

confidence: 99%

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Disorder and Dynamics in Pollucite from ¹³³Cs and ²⁷Al NMR

Ashbrook

Whittle

Pollès

et al. 2005

Journal of the American Ceramic Society

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Pollucite, CsAlSi2O6, a Cs polymorph of leucite (KAlSi2O6), has been proposed for ceramic immobilization of 135Cs and 137Cs fission products. 133Cs NMR of both low‐ (tetragonal) and high‐temperature (cubic) forms of pollucite exhibit a considerable distribution of local Cs environments. 29Si and 27Al NMR data from directly prepared pollucite show greater Al/Si disorder than either leucite, or pollucite produced by ion exchange. Little evidence for Cs motion is observed in tetragonal or cubic pollucite, and only at high temperatures (∼850°C) is any substantial dynamic behavior detected. Dynamic NMR lineshape calculations allow a determination of the frequency of Cs motion and diffusivity.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Disorder and Dynamics in Pollucite from ¹³³Cs and ²⁷Al NMR

Ashbrook

Whittle

Pollès

et al. 2005

Journal of the American Ceramic Society

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“…For half-integer quadrupolar nuclei the effect of dynamics may be probed by analysis of the central transition [45][46][47][48][49]. This transition is not influenced by the first-order quadrupolar interaction but only by the secondorder quadrupolar interaction.…”

Section: Article In Pressmentioning

confidence: 99%

Simulations of molecular dynamics in solid-state NMR spectra of spin-1 nuclei including effects of CSA- and EFG-terms up to second order

Larsen

2007

Solid State Nuclear Magnetic Resonance

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“…For systems subject to molecular motion the lineshapes and relaxation times may be simulated using the density operator that is obtained as the solution to the stochastic Liouville-von Neumann equation. [28][29][30] This includes the Hamiltonian that represents the nuclear spin interactions as well as the stochastic operator that describes the details of the The most important and successful methods to study molecular motions and spin diffusion include techniques to measure the relaxation of the longitudinal magnetization and longitudinal magnetization in the rotating frame. These methods are sensitive to different motional regimes and may provide information about structural and motional inhomogeneity.…”

Section: Nmr Analysismentioning

confidence: 99%

Solid state 13C CP MAS NMR study of molecular motions and interactions of urea adsorbed on cotton cellulose

Kristensen

Bampos

Duer

2004

Phys. Chem. Chem. Phys.

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The surface interaction between cotton cellulose and urea was studied by measuring solid state 13 C CP MAS NMR spectra and relaxation times. The investigation of cotton cellulose surface interactions is inherently difficult as the surface regions constitute only a small proportion of cotton fibers and an important part of these investigations has been to identify and develop useful experimental methods. The results have provided detailed insight into the interactions and motions of urea at the cotton cellulose surface. It is found that the interactions have no discernible effects on the crystallinity and polymorphic form of cellulose. This suggests that urea does not penetrate the cellulose microfibrils and distort the internal hydrogen bonding structure but interact with the cotton cellulose surface. The relaxation techniques used in this paper make it possible to identify several cellulose components including the crystalline and amorphous regions that are not directly resolved in the spectra. Another advantage of the relaxation methods is that it becomes possible to study details of molecular motion in both the crystalline and amorphous regions that may be related to the mechanical properties of the cellulose microfibrils. It has been possible to describe the surface interaction between urea and cotton cellulose in terms of the motion of the urea molecules. The interaction at the cotton cellulose surface makes the urea molecules more mobile as revealed by the lineshapes and relaxation characteristics. The study of the motion makes it possible to obtain a description of the orientation of the urea molecules at the cotton cellulose surface. This orientation is determined by numerous intermolecular interactions and provides a constraint on the intermolecular potential. The results suggest that the urea molecules interact preferentially at hydrophilic defects on the surface such as depressions and grooves by hydrogen bonding with surface hydroxyl groups. The shape of these surface defects is directly reflected in the orientation of the urea molecules at the binding sites. The experiments have been shown to be selective, monitoring only urea molecules interacting with the cotton cellulose surface. This makes urea an excellent probe molecule to study cotton cellulose surfaces.

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Anisotropic relaxation and motion of half-integer quadrupole nuclei studied by central transition nuclear magnetic resonance spectroscopy

Cited by 15 publications

References 39 publications

Disorder and Dynamics in Pollucite from ¹³³Cs and ²⁷Al NMR

Disorder and Dynamics in Pollucite from ¹³³Cs and ²⁷Al NMR

Simulations of molecular dynamics in solid-state NMR spectra of spin-1 nuclei including effects of CSA- and EFG-terms up to second order

Solid state 13C CP MAS NMR study of molecular motions and interactions of urea adsorbed on cotton cellulose

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Anisotropic relaxation and motion of half-integer quadrupole nuclei studied by central transition nuclear magnetic resonance spectroscopy

Cited by 15 publications

References 39 publications

Disorder and Dynamics in Pollucite from 133Cs and 27Al NMR

Disorder and Dynamics in Pollucite from 133Cs and 27Al NMR

Simulations of molecular dynamics in solid-state NMR spectra of spin-1 nuclei including effects of CSA- and EFG-terms up to second order

Solid state 13C CP MAS NMR study of molecular motions and interactions of urea adsorbed on cotton cellulose

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Disorder and Dynamics in Pollucite from ¹³³Cs and ²⁷Al NMR

Disorder and Dynamics in Pollucite from ¹³³Cs and ²⁷Al NMR