A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
Deuteron NMR spectra and relaxation in fully and partly deuterated (NH4)(2)ZnCl4
Tekijät: Stoch G, Ylinen EE, Punkkinen M, Petelenz B, Birczynski A
Kustantaja: ACADEMIC PRESS INC ELSEVIER SCIENCE
Julkaisuvuosi: 2009
Lehti:: Solid State Nuclear Magnetic Resonance
Tietokannassa oleva lehden nimi: SOLID STATE NUCLEAR MAGNETIC RESONANCE
Lehden akronyymi: SOLID STATE NUCL MAG
Vuosikerta: 35
Numero: 3
Aloitussivu: 180
Lopetussivu: 186
Sivujen määrä: 7
ISSN: 0926-2040
DOI: https://doi.org/10.1016/j.ssnmr.2008.12.009
Tiivistelmä
Deuteron NMR spectra and relaxation were studied at the resonance frequency of 46MHz in polycrystalline fully and partly deuterated (NH4)(2)ZnCl4 between 300 and 5 K. Spectral components confirm existence of ammonium positions with different potential symmetry, resulting in two- and threefold reorientation of ammonium ions. The temperature dependence of the spin-lattice relaxation rate discloses two time constants in the whole range. The fitting procedure allows the separation into contributions from subsystems of ions in respective potentials. Two relaxation rate maxima are attributed to ions performing threefold uniaxial reorientation at low temperatures. The lower-temperature maximum is observed at T <= 36 K. With increasing temperature reorientations about remaining axes start to contribute leading to the other maximum near 100 K. The other category of ammonium ions gives rise to the maximum at about 50 K. Below this temperature the dominant motion seems to be 180 reorientations about one twofold axis according to observed spectra. Consistent picture of ion mobility is accomplished for 5%, 30%, 70% and 100% deuterated compounds. (c) 2008 Elsevier Inc. All rights reserved.
Deuteron NMR spectra and relaxation were studied at the resonance frequency of 46MHz in polycrystalline fully and partly deuterated (NH4)(2)ZnCl4 between 300 and 5 K. Spectral components confirm existence of ammonium positions with different potential symmetry, resulting in two- and threefold reorientation of ammonium ions. The temperature dependence of the spin-lattice relaxation rate discloses two time constants in the whole range. The fitting procedure allows the separation into contributions from subsystems of ions in respective potentials. Two relaxation rate maxima are attributed to ions performing threefold uniaxial reorientation at low temperatures. The lower-temperature maximum is observed at T <= 36 K. With increasing temperature reorientations about remaining axes start to contribute leading to the other maximum near 100 K. The other category of ammonium ions gives rise to the maximum at about 50 K. Below this temperature the dominant motion seems to be 180 reorientations about one twofold axis according to observed spectra. Consistent picture of ion mobility is accomplished for 5%, 30%, 70% and 100% deuterated compounds. (c) 2008 Elsevier Inc. All rights reserved.
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