A1 Refereed original research article in a scientific journal
Deuteron spin-lattice relaxation in partially deuterated ammonium hexachlorotellurate
Authors: Birczynski A, Lalowicz ZT, Punkkinen M, Szymocha AM
Publisher: ELSEVIER SCIENCE BV
Publication year: 2006
Journal:: Chemical Physics
Journal name in source: CHEMICAL PHYSICS
Journal acronym: CHEM PHYS
Volume: 327
Issue: 2-3
First page : 373
Last page: 384
Number of pages: 12
ISSN: 0301-0104
DOI: https://doi.org/10.1016/j.chemphys.2006.05.011
Abstract
Deuteron spin-lattice relaxation is studied both theoretically and experimentally in polycrystalline samples of ammonium hexachlorotellurate with deuteron concentrations ranging from 5% to 100%. A model is derived for the initial deuteron relaxation rate, via the electric quadrupole interaction, under the assumption that the static part of the rotational Hamiltonian and ammonium rotation obeys the same symmetry. The obtained result reveals a possibility for maxima in the relaxation rate at level crossings, where the deuteron resonance frequency equals g vertical bar h(i)(') - h(j)(')vertical bar with g = 1/2, 1 or 2. The tunelling matrix element produces the tunnel splitting 3 vertical bar h(j)(')vertical bar for the three NH3D+ protons when the deuteron is at the equilibrium position j. The relaxation rates via the deuteron-proton magnetic dipolar interaction is considered. Experimental results are explained by the above model based on the quadrupole interaction at higher deuterations and by so-called limited jumps at lower deuterations. Limited jumps mean a restricted rotation of the rigid ammonium ion in such a way that the nitrogen-hydrogen bonds make always a certain angle with the nearest nitrogen-tellurium direction. Our interpretation of relaxation rates agrees with the details of deuteron NMR spectra. (c) 2006 Elsevier B.V. All rights reserved.
Deuteron spin-lattice relaxation is studied both theoretically and experimentally in polycrystalline samples of ammonium hexachlorotellurate with deuteron concentrations ranging from 5% to 100%. A model is derived for the initial deuteron relaxation rate, via the electric quadrupole interaction, under the assumption that the static part of the rotational Hamiltonian and ammonium rotation obeys the same symmetry. The obtained result reveals a possibility for maxima in the relaxation rate at level crossings, where the deuteron resonance frequency equals g vertical bar h(i)(') - h(j)(')vertical bar with g = 1/2, 1 or 2. The tunelling matrix element produces the tunnel splitting 3 vertical bar h(j)(')vertical bar for the three NH3D+ protons when the deuteron is at the equilibrium position j. The relaxation rates via the deuteron-proton magnetic dipolar interaction is considered. Experimental results are explained by the above model based on the quadrupole interaction at higher deuterations and by so-called limited jumps at lower deuterations. Limited jumps mean a restricted rotation of the rigid ammonium ion in such a way that the nitrogen-hydrogen bonds make always a certain angle with the nearest nitrogen-tellurium direction. Our interpretation of relaxation rates agrees with the details of deuteron NMR spectra. (c) 2006 Elsevier B.V. All rights reserved.
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