ChemInform Abstract: SOLVENT DEPENDENCE OF THE DEUTERON QUADRUPOLE COUPLING CONSTANT OF TRICHLOROMETHANE-D1 DETERMINED BY DEUTERIUM SPIN-LATTICE RELAXATION AND RAMAN LINE SHAPE STUDIES

1985 ◽  
Vol 16 (19) ◽  
Author(s):  
R. V. GREGORY ◽  
M. R. ASDJODI ◽  
H. G. SPENCER ◽  
A. L. BEYERLEIN ◽  
G. B. SAVITSKY
Keyword(s):  
Raman Line ◽  
Line Shape ◽  
Lattice Relaxation ◽  
Quadrupole Coupling Constant ◽  
Spin Lattice Relaxation ◽  
Coupling Constant ◽  
Spin Lattice ◽  
Solvent Dependence ◽  
Quadrupole Coupling

Deuteron Relaxation Study of the Reorienting Methyl Groups in p-Azoxyanisole

1974 ◽  
Vol 52 (12) ◽  
pp. 2294-2295 ◽  
Author(s):  
M. Wiszniewska ◽  
Ronald Y. Dong ◽  
E. Tomchuk ◽  
E. Bock
Keyword(s):  
Relaxation Times ◽  
Lattice Relaxation ◽  
Quadrupole Coupling Constant ◽  
Spin Lattice Relaxation ◽  
Isotropic Phase ◽  
Coupling Constant ◽  
Spin Lattice ◽  
Quadrupole Coupling ◽  
Relaxation Study ◽  
Deuteron Spin

The deuteron spin-lattice relaxation times were measured in the nematic and isotropic phases of p-azoxyanisole(CD3)2. An apparent activation energy for the methyl group reorientation in the isotropic phase is obtained. The quadrupole coupling constant along the C—D bond is found to be 147 ± 8 kHz.

Sodium NMR in the trigonal phase of sodium hydrosulfide

1976 ◽  
Vol 54 (16) ◽  
pp. 1651-1659 ◽  
Author(s):  
Kenneth R. Jeffrey ◽  
Stanley L. Segel
Keyword(s):  
Phase Transition ◽  
Lattice Relaxation ◽  
Quadrupole Coupling Constant ◽  
Spin Lattice Relaxation ◽  
Trigonal Axis ◽  
Coupling Constant ◽  
Spin Lattice ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole ◽  
Trigonal Phase

Measurements of the sodium nuclear quadrupole coupling constant and spin–lattice relaxation time, while confined mainly to the trigonal phase, show the existence of the two known phase transitions at 358 and 113 K. The quadrupole coupling constant is 206 kHz at 358 K and decreases roughly linearly with decreasing temperature at a rate of about 0.66 kHz/K. The satellite peaks in the quadrupolar split powder pattern disappear above 358 K in the cubic phase. Below 130 K. where there is no known phase transition, the satellites broaden and again disappear but in this case it is because the fluctuation rate of the electric field gradient at the sodium site due to reorientation of the SH− ion is about equal to the quadrupolar splitting of the spectrum at this temperature. Only the resonance from the −1/2 ↔ 1/2 transition is observed down to 77 K.The spin–lattice relaxation of the sodium spins shows a very strong temperature dependence and a well-defined minimum similar to the previously observed results for the protons. The relaxation is caused by the nuclear quadrupole interaction made time dependent by the reorientation of the neighbouring SH− ions. A simple model calculation gives reasonable agreement between the calculated and experimental values of T1 at the minimum if the SH− ion is considered to move between two positions parallel and antiparallel to the trigonal axis. An extension of this model suggests that the lack of an enhanced relaxation rate at the 113 K phase transition may be a result of a parallel ordering of neighbouring SH− ions along the trigonal axis in the lowest temperature phase.

Elektronen-Spin-Resonanz von Mn2+-Ionen im kubischen und trigonalen Kristallfeld des ZnS

1963 ◽  
Vol 18 (8-9) ◽  
pp. 980-993 ◽  
Author(s):  
Jürgen Schneider ◽  
Subhas Ranjan Sircar ◽  
Armin Räuber
Keyword(s):  
Lattice Relaxation ◽  
Quadrupole Coupling Constant ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Coupling Constant ◽  
Spin Lattice ◽  
Uv Illumination ◽  
X Band ◽  
Quadrupole Coupling ◽  
Spin Resonance

The Electron-Spin-Resonance of Mn2+-ions in synthetic cubic and hexagonal ZnS crystals has been observed at X-band frequencies. At 300°K the following values for the parameters of the Spin-HAMILTONian resulted for cubic ZnS:g=2,0024±0,0003, α= +0,000787 ± 0,000006 cm-1, A= -0,00640±0,00001 cm-1.A weak superhyperfine structure due to an interaction of the 3d-electrons of the Mn2+-ion with the surrounding Zn67-nuclei was also resolved. The influence of stacking faults in cubic ZnS crystals on the position and linewidth of the Mn2+-spectrum was investigated in detail.For hexagonal ZnS we found at 300°K:g∥ =2,0018 ± 0,0003, a— F = + 0,000768 ± 0,00001 cm-1,α = +0,000735 ± 0,00001 cm-1, A = —0,00649 ± 0,00001 cm-1,D= —0,01309 ± 0,00003 cm-1, P=+ 0,000010±0,000002 cm-1.The quadrupole coupling constant P was determined from forbidden Am= ± 1 transitions. A strong decrease of the spin-lattice relaxation time of the Mn2+-ion was observed in photoconducting ZnS crystals under uv-illumination at 77°K.

17O Quadrupole Dips in Ammonium Persulphate

1994 ◽  
Vol 49 (1-2) ◽  
pp. 345-350 ◽  
Author(s):  
N. F. Peirson ◽  
J. A. S. Smith ◽  
D. Stephenson
Keyword(s):  
Relaxation Time ◽  
Lattice Relaxation ◽  
Quadrupole Coupling Constant ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Ammonium Persulphate ◽  
Spin Lattice Relaxation Time ◽  
Spin Lattice ◽  
Resonance Frequencies ◽  
Quadrupole Coupling

Abstract The magnetic field dependence of the 1H spin-lattice relaxation time in ammonium persulphate shows pronounced minima near the 1H magnetic resonance frequencies of 1,200 and 2,200 kHz. These are interpreted in terms of a model involving cross-relaxation between 1H in the NH4 ion and 17O in natural abundance in the S2O2-8 ions, the latter having a much shorter spin-lattice relaxation time. A theoretical analysis of the shape of the minima is used to derive values for the 17O quadrupole parameters. This analysis results in best estimate values for the quadrupole coupling constant of 6.75 (± 0.05) MHz and an asymmetry of 0.30 (± 0.02). Such values are indicative o f O-H hydrogen bonding and suggest the S2O2-8 ion is not undergoing rapid reorientation at temperatures below 320 K.

2 D Methods in NQR Spectroscopy

1992 ◽  
Vol 47 (1-2) ◽  
pp. 333-341
Author(s):  
J. Seliger ◽  
R. Blinc
Keyword(s):  
Double Resonance ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Electric Quadrupole ◽  
Quadrupole Coupling Constant ◽  
Spin Lattice Relaxation ◽  
Two Dimensional ◽  
Spin Lattice ◽  
Quadrupole Coupling ◽  
Field Cycling

AbstractThe application of two-dimensional spectroscopy to nuclear quadrupole resonance (NQR) is reviewed with special emphasys on spin 3/2 nuclei. A new two-dimensional level crossing double resonance NQR nutation technique based on magnetic field cycling is described. This technique allows for a determination of both the electric quadrupole coupling constant and the asymmetry parameter for spin 3/2 nuclei in powdered samples even in cases where the quadrupolar signals are too weak to be observed directly. It works if the usual double resonance conditions are met, i.e. if the spin-lattice relaxation times are not too short if the quadrupolar nuclei are dipolarly coupled to "strong" nuclei. Variations of this techique can be also used for 2 D "exchange" NQR spectroscopy and NQR imaging.

Applications of 95Mo N.M.R. Spectroscopy. XVIII. Relaxation Times, Quadrupole Coupling Constants and Partial Field Gradients in [Mo(CO)5L] Complexes

1988 ◽  
Vol 41 (9) ◽  
pp. 1457 ◽  
Author(s):  
RTC Brownlee ◽  
BP Shehan ◽  
AG Wedd
Keyword(s):  
Relaxation Times ◽  
Lattice Relaxation ◽  
Quadrupole Coupling Constant ◽  
Coupling Constants ◽  
Spin Lattice Relaxation ◽  
Scalar Coupling ◽  
Spin Lattice ◽  
Field Gradients ◽  
Pyridine Complex ◽  
Quadrupole Coupling

A study of ,95Mo spin-lattice relaxation times (T1) and linewidths of [Mo(CO)5L] complexes, where L = PPh3, AsPh3, SbPh3, pyridine and Cl-, has shown that the relaxation times are due entirely to the quadrupolar mechanism, with no scalar coupling contribution to linewidth where molybdenum is bonded to a quadrupolar nucleus. Based on the literature value of the quadrupole coupling constant obtained by n.q.r . for the PPh3 complex (1.972 MHz), the quadrupole coupling constants of the arsine and stibine complexes are determined to be 3.36 and 3.75 MHz respectively. These values, and that of the pyridine complex (2.80 MHz), are found to correlate with ligand partial field gradient parameters obtained from Mossbauer spectra of FeII complexes, and are rationalized in terms of metal- ligand bonding interactions. For Et4N [Mo(CO)5Cl], the correlation is very poor; this result is attributed to the effects of ion in solution.

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