Deuteron NMR spectra of ND4ClO4 single crystal at low temperatures.
2H NMR spectra of ND4ClO4 single crystal were obtained at v0 = 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.
Birczyński
A
A
Niewodniczański Institute of Nuclear Physics, Kraków, Poland.
Lalowicz
Z T
ZT
Ingman
L P
LP
Punkkinen
M
M
Ylinen
E E
EE
D003080:Cold Temperature; D003460:Crystallization; D003903:Deuterium / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008956:Models, Chemical; D015394:Molecular Structure; D010472:Perchlorates / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics
D010472:Perchlorates; D000644:Quaternary Ammonium Compounds; D003903:Deuterium; C053506:ammonium perchlorate