Relaxation Times and Saturation of Nuclear Quadrupole Resonance of 14N in Asymmetric Field Gradients

1969 ◽  
Vol 51 (1) ◽  
pp. 461-463 ◽  
Author(s):  
C. T. O'Konski ◽  
K. Torizuka
Keyword(s):  
Nuclear Quadrupole Resonance ◽  
Relaxation Times ◽  
Field Gradients ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

scholarly journals Tris(2-Methoxyphenyl)Bismuthine Polymorphism Characterized by Nuclear Quadrupole Resonance Spectroscopy

Crystals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 446
Author(s):  
Scharfetter ◽  
Fischer ◽  
Krassnig ◽  
Thonhofer ◽  
Theyer ◽  
...  
Keyword(s):  
Nuclear Quadrupole Resonance ◽  
Relaxation Times ◽  
Crystallographic Structure ◽  
Resonance Spectroscopy ◽  
Monoclinic Space Group ◽  
Asymmetric Unit ◽  
Slow Cooling ◽  
Quadrupole Resonance ◽  
Potential Formation ◽  
Nuclear Quadrupole

Based on the previous identification of metastable polymorphs in crystalline triphenylbismuth by nuclear quadrupole resonance spectroscopy (NQRS), the potential formation of similar phases was studied in Tris(2-Methoxyphenyl)Bismuthine. To this end, commercial samples with known NQRS properties were molten and re-crystallized at different speeds (shock freezing in different coolants versus slow cooling inside of a heater). In all recrystallization products we have identified a new crystal phase which has not been observed after synthesis from a solution. The new crystallographic structure has been confirmed by X-ray diffraction (XRD). The newly isolated polymorph crystallizes in the monoclinic space group P2(1)/c with only one molecule in the asymmetric unit and consequently only one 5/2-7/2 transition is observed at 88.75 MHz at 310 K. In contrast, the two transitions at 89.38 and 89.29 MHz for the well-known trigonal polymorph originate from two crystallographically distinct molecules of Tris(2-methoxy-Phenyl)Bismuthine in the asymmetric unit. Additional relaxometric NQRS shows distinctly different T2 relaxation times for the new polymorph when compared to the original samples. Additional phase transitions could not be observed during temperature sweeps between 153K and 323K.

scholarly journals Measurement of Apparent Spin?Spin Relaxation Times in Nuclear Quadrupole Resonance Using a Double Pulsed Super-regenerative Oscillator

1975 ◽  
Vol 28 (1) ◽  
pp. 45 ◽  
Author(s):  
KR Doolan ◽  
S Hacobian
Keyword(s):  
Nuclear Quadrupole Resonance ◽  
Spin Relaxation ◽  
Mathematical Analysis ◽  
Relaxation Times ◽  
Modes Of Operation ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole ◽  
T Values

A super-regenerative oscillator has been used to obtain apparent spin-spin relaxation times n for nuclear quadrupole resonance signals from some polycrystalline compounds. A mathematical analysis is given to show how T~ values may be obtained from a double pulsed super-regenerative oscillator for both logarithmic and linear modes of detection; each of these modes is described. Results obtained from both modes of operation are examined.

An arsenic-75 nuclear quadrupole resonance study of α and β As4S3

1972 ◽  
Vol 25 (11) ◽  
pp. 2291 ◽  
Author(s):  
TJ Bastow ◽  
ID Campbell ◽  
HJ Whitfield
Keyword(s):  
Thermal Expansion ◽  
Temperature Dependence ◽  
Nuclear Quadrupole Resonance ◽  
Electrostatic Field ◽  
Β Phase ◽  
Field Gradients ◽  
Α Phase ◽  
Resonance Frequencies ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

The nuclear quadrupole resonance frequencies of 75As in the α and β forms of As4S3 have been measured at 77, 195, and 293 K. The frequencies at 77 K were: α phase 64.87 65.94 79.56 MHz β phase 65.42 67.16 79.65 MHz An analysis is presented in terms of Townes-Dailey theory and of the temperature dependence in terms of Bayer-Brown theory. The differences in frequencies of the α and β forms were attributed to the effect of electrostatic field gradients, estimated by lattice sums. Allowance must be made for the thermal expansion of the lattice to obtain a consistent interpretation.

scholarly journals The Predictive Power of Different Projector-Augmented Wave Potentials for Nuclear Quadrupole Resonance

Crystals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 507 ◽  
Author(s):  
Jaafar N. Ansari ◽  
Karen L. Sauer ◽  
James K. Glasbrenner
Keyword(s):  
Nuclear Quadrupole Resonance ◽  
Density Functional ◽  
Predictive Ability ◽  
Transition Elements ◽  
Field Gradients ◽  
Resonance Frequencies ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole ◽  
Experimental Values ◽  
Projector Augmented Wave

The projector-augmented wave (PAW) method is used to calculate electric field gradients (EFG) for various PAW potentials. A variety of crystals containing reactive nonmetal, simple metal, and transition elements, are evaluated in order to determine the predictive ability of the PAW method for the determination of nuclear quadrupole resonance frequencies in previously unstudied materials and their polymorphs. All results were compared to experimental results and, where possible, to previous density functional theory (DFT) calculations. The EFG at the 14N site of NaNO2 is calculated by DFT for the first time. The reactive nonmetal elements were not very sensitive to the variation in PAW potentials, and calculations were quite close to experimental values. For the other elements, the various PAW potentials led to a clear spread in EFG values, with no one universal potential emerging. Within the spread, there was agreement with other ab initio models.

NUCLEAR QUADRUPOLE RESONANCE STUDIES IN CUPROUS OXIDE

1966 ◽  
Vol 44 (10) ◽  
pp. 2315-2328 ◽  
Author(s):  
K. R. Jeffrey ◽  
R. L. Armstrong
Keyword(s):  
Nuclear Quadrupole Resonance ◽  
Cuprous Oxide ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Quadrupole Moments ◽  
Spin Lattice ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

The 63Cu and 65Cu pure nuclear quadrupole resonance transitions have been investigated in a powder sample of cuprous oxide from 4.2 °K to 298 °K. The observed decrease in resonance frequency with increasing temperature is discussed in terms of the theory developed by Bayer and Kushida. The spin-lattice relaxation-time measurements above 20.4 °K are interpreted in terms of a coupling of the lattice phonons to the nuclear quadrupole moments via two phonon Raman processes. A rough estimate of the Debye temperature is made. The measured relaxation times at 4.2 °K are an order of magnitude shorter than predicted by the spin-phonon mechanism. Two other mechanisms are discussed: (i) a coupling of the spins to torsional oscillations; (ii) a coupling of the spins to paramagnetic impurities.

Application of Nuclear Quadrupole Resonance Relaxometry to Study the Influence of the Environment on the Surface of the Crystallites of Powder

2015 ◽  
Vol 70 (6) ◽  
pp. 451-457 ◽  
Author(s):  
Nikolay Ya. Sinyavsky ◽  
Ivan G. Mershiev ◽  
Galina S. Kupriyanova
Keyword(s):  
Nuclear Quadrupole Resonance ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Inverse Laplace Transform ◽  
Spin Lattice Relaxation ◽  
Two Dimensional ◽  
Surface Phenomena ◽  
Spin Lattice ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

AbstractThe results of the experimental study of the influence of the environment surrounding the surface of the crystallites of a KClO3 powder on the distribution of the spin–spin and spin–lattice relaxation times for 35Cl nuclear quadrupole resonance are described. It was found that the distributions of the spin–lattice relaxation times are unimodal and distributions of the spin–spin relaxation times are bimodal for all samples we studied. T1 – T2 and T1ρ – T2 correlations by means of the two-dimensional (2D) inverse Laplace transform are obtained. The efficiency of the method for the study of surface phenomena in solids is demonstrated.

Sign in / Sign up

Export Citation Format

Share Document