Comment on the Letter ``Measurement of Molecular Rotation by 14N Nuclear Quadrupole Resonance Relaxation Times''

1965 ◽  
Vol 42 (9) ◽  
pp. 3341-3342 ◽  
Author(s):  
George W. Smith
Keyword(s):  
Nuclear Quadrupole Resonance ◽  
Relaxation Times ◽  
Molecular Rotation ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole ◽  
Resonance Relaxation

A nuclear quadrupole resonance investigation of the effect of pressure on molecular rotation in K2PtCl6

1969 ◽  
Vol 47 (10) ◽  
pp. 1095-1100 ◽  
Author(s):  
R. L. Armstrong ◽  
K. R. Jeffrey
Keyword(s):  
Resonance Frequency ◽  
Nuclear Quadrupole Resonance ◽  
Activation Volume ◽  
Classical Model ◽  
Nuclear Quadrupole Resonance Frequency ◽  
Molecular Rotation ◽  
A Value ◽  
Quadrupole Resonance ◽  
Quadrupolar Relaxation ◽  
Nuclear Quadrupole

The pressure dependences of the 35Cl quadrupolar relaxation rate and nuclear quadrupole resonance frequency in K2PtCl6 are measured for hydrostatic pressures up to 5000 kg cm−2 at six temperatures. The temperatures were selected so that the effects of pressure on the rotation of PtCl6 groups could be investigated. The relaxation resulting from the molecular rotation is discussed in terms of the simple classical model of an activated process. An activation volume ΔV* = 25.6 cm3 mole−1 for the rotation is deduced. The effect of the onset of the rotation on the nuclear quadrupole resonance frequency is noted. The results are shown to be consistent with earlier measurements on the 14N resonance in (CH2)6N4. The activation energy ΔE* for the rotation is shown to have a value between 12.6 and 18.8 kcal mole−1.

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.

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.

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