A1 Refereed original research article in a scientific journal
Deuteron NMR spectra of ND4ClO4 single crystal at low temperatures
Authors: Birczynski A, Lalowicz ZT, Ingman LP, Punkkinen M, Ylinen EE
Publisher: ACADEMIC PRESS INC ELSEVIER SCIENCE
Publication year: 1993
Journal:: Solid State Nuclear Magnetic Resonance
Journal name in source: SOLID STATE NUCLEAR MAGNETIC RESONANCE
Journal acronym: SOLID STATE NUCL MAG
Volume: 1
Issue: 6
First page : 329
Last page: 344
Number of pages: 16
ISSN: 0926-2040
DOI: https://doi.org/10.1016/0926-2040(93)90015-F
Abstract
H-2 NMR spectra of ND4ClO4 single crystal were obtained at v(0) = 44 MHz. Orientation and temperature (1.9-75 K) dependences were measured. Fitting the spectra gives the effective quadrupole coupling constants for all deuterons and the ground torsional level structure. The isotope reduction of the (A-T) and (A-E) tunnelling splittings, i.e., the ratios of the respective splittings for NH4+ and ND4+, were found to be different. The splittings at T = 24 K are about 60% of the helium temperature values. The spectrum undergoes intermediate narrowing by reorientations between 26 and 34 K and tunnelling related features in the spectra are eradicated. After reaching the extreme narrowing limit, a doublet with gradually decreasing separation was observed, what was attributed to averaging by torsional oscillations of increasing amplitude. At high temperatures (T > 75 K), the narrow spectrum reflects fast multiaxial reorientation of the ammonium ion.
H-2 NMR spectra of ND4ClO4 single crystal were obtained at v(0) = 44 MHz. Orientation and temperature (1.9-75 K) dependences were measured. Fitting the spectra gives the effective quadrupole coupling constants for all deuterons and the ground torsional level structure. The isotope reduction of the (A-T) and (A-E) tunnelling splittings, i.e., the ratios of the respective splittings for NH4+ and ND4+, were found to be different. The splittings at T = 24 K are about 60% of the helium temperature values. The spectrum undergoes intermediate narrowing by reorientations between 26 and 34 K and tunnelling related features in the spectra are eradicated. After reaching the extreme narrowing limit, a doublet with gradually decreasing separation was observed, what was attributed to averaging by torsional oscillations of increasing amplitude. At high temperatures (T > 75 K), the narrow spectrum reflects fast multiaxial reorientation of the ammonium ion.
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