Tone-Bursting of Quadrupolar Nuclei. Determination of the Spin–Lattice Relaxation Times in Ferroelectric Lithium Tantalate and Lithium Niobate

1972 ◽  
Vol 50 (10) ◽  
pp. 966-975 ◽  
Author(s):  
J. D. Stroud ◽  
R. B. Creel ◽  
S. L. Segel ◽  
R. J. Schoenberger
Keyword(s):  
Lithium Niobate ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Electric Quadrupole ◽  
Lithium Tantalate ◽  
Spin Lattice Relaxation ◽  
Quadrupolar Nuclei ◽  
Quadrupole Relaxation ◽  
Spin Lattice

The technique of "tone-bursting" for the determination of spin–lattice relaxation times has been extended to quadrupolar nuclei and applied to two ferroelectric crystals: lithium tantalate and lithium niobate. The approach has been to analytically follow the populations of the Zeeman quadrupole levels through each passage through resonance and determine the effective T1 from the decrease in magnetization. The analytic results agree with the computer results obtained by Creel and Barnes. The results also agree with the conclusion of Walstedt that the relaxation rate is enhanced by a factor of [Formula: see text] when only the central resonance is being irradiated in a quadrupolar split pattern.Application of the technique to 7LiTaO3 yields a value of 3.0 ± 1.0 s for the effective T1, dominated by magnetic dipole relaxation. For 7LiNbO3, the effective T1 is 33 ± 5.0 s for the central transition and the relaxation mechanism is predominantly electric quadrupole relaxation.

A Selective Determination of the Proton Nuclear Relaxation Times of the Alkaloid Vindoline: An Extension via Fourier Transform Measurements

1974 ◽  
Vol 52 (5) ◽  
pp. 829-832 ◽  
Author(s):  
L. D. Hall ◽  
Caroline M. Preston
Keyword(s):  
Fourier Transform ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Nuclear Relaxation ◽  
Transform Method ◽  
Fourier Transform Method ◽  
Selective Determination ◽  
Spin Lattice

A Fourier Transform method has been used to measure the spin–lattice relaxation times of essentially all the protons of the alkaloid, vindoline. It is shown that even for a molecule of this size substantial and potentially useful differences exist in the experimental relaxation times which reflect the degree of crowding of each proton by other protons.

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.

The determination of zero-field splittings from measurements of spin-lattice relaxation times

1974 ◽  
Vol 35 (5) ◽  
pp. 73-76 ◽  
Author(s):  
A.M. Vasson ◽  
A. Vasson ◽  
A. Gavaix ◽  
T.S. Yalcin ◽  
P. Steggles ◽  
...  
Keyword(s):  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Zero Field ◽  
Spin Lattice

Temperature Dependences of NQR Frequencies and Nuclear Quadrupole Relaxation Times of Chlorine in 2,6-Lutidinium Hexachlorotellurate (IV) as Studied by Pulsed NQR Techniques

1990 ◽  
Vol 45 (3-4) ◽  
pp. 485-489
Author(s):  
Keizo Horiuchi ◽  
Takashige Shimizu ◽  
Hitomi Iwafune ◽  
Tetsuo Asaji ◽  
Daiyu Nakamura
Keyword(s):  
Phase Transition ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Temperature Phase ◽  
Quadrupole Relaxation ◽  
Spin Lattice ◽  
Resonance Frequencies ◽  
Temperature Dependences ◽  
Nuclear Quadrupole

Abstract The temperature dependences of the 35Cl NQR frequencies vQ and the nuclear quadrupole spin-lattice relaxation times T1Q in 2,6-lutidinium hexachlorotellurate (IV) was observed at various temperatures between 80 and 343 K. This crystal undergoes a phase transition at Tc = 229 K. A single and three pairs of 35Cl NQR frequencies were observed above and below Tc , respectively. The hysteresis of the phase transition and a discontinuity in the temperature dependence of the resonance frequencies at Tc indicate that this phase transition is of first order. Although the resonance frequencies of the pairs in the low temperature phase are very close to one another, T1Q and below Tc could be accurately determined by measuring the Fourier transform spectra of each line. Above ca. 250 K, T1Q showed an exponential decrease which is attributable to the overall reorientational motion of [TeCl6]2- with an activation energy of 82 kJ mol-1

Determination of anisotropy of molecular motion with carbon-13 spin-lattice relaxation times

1975 ◽  
Vol 97 (7) ◽  
pp. 1805-1808 ◽  
Author(s):  
Stefan Berger ◽  
Fritz R. Kreissl ◽  
David M. Grant ◽  
John D. Roberts
Keyword(s):  
Molecular Motion ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice
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