Topic
Nuclear quadrupole resonance
About: Nuclear quadrupole resonance is a research topic. Over the lifetime, 3531 publications have been published within this topic receiving 38801 citations. The topic is also known as: Nuclear quadrupole resonance spectroscopy & NQR.
Papers published on a yearly basis
Papers
More filters
••
TL;DR: In this paper, the nuclear spin-lattice relaxation rate 1/T-1 shows a well-defined coherence peak below T-c and decreases exponentially at low temperatures.
Abstract: We report Pt-195-NMR and As-75 nuclear quadrupole resonance measurements for the locally noncentrosymmetric superconductor SrPtAs where the As-Pt layer breaks inversion symmetry while globally the compound is centrosymmetric. The nuclear spin-lattice relaxation rate 1/T-1 shows a well-defined coherence peak below T-c and decreases exponentially at low temperatures. The spin susceptibility measured by the Knight shift also decreases below Tc down to T < T-c/6. These data, together with the penetration depth obtained from the NMR spectra, can be consistently explained by a spin-singlet superconducting state with a full gap. Our results suggest that the spin-orbit coupling due to the local inversion-symmetry breaking is not large enough to bring about an exotic superconducting state, or the interlayer hopping interaction is larger than the spin-orbit coupling.
23 citations
••
22 citations
••
01 Jan 1972TL;DR: The crystal field effect is of the order of δv (35Cl) = ±500 kHz in Cl atoms bound to carbon as discussed by the authors, which is equivalent to an increasing antishielding factor γ∞ for Cl.
Abstract: A quantitative investigation of the crystal field effect is quite difficult. From the large number of NQR measurements available, the following qualitative conclusions can be drawn.
a)
The crystal field effect is of the order of δv (35Cl) = ±500 kHz in Cl atoms bound to carbon.
b)
With increasing ionic character of a bond Cl-X, the crystal field effects become more pronounced, because the multipole moments of the molecules in the lattice and the quadrupole polarizability of the core electrons of the 35Cl nucleus increase. This second point is equivalent to an increasing antishielding factor γ∞ for Cl.
c)
Quantitative calculations of the charge transfer in molecular compounds or of the ionic character induced within a molecule through the formation of the complex are only possible if the crystal structure is known and single-crystal NQR data (including η) are available. From NQR powder data, only qualitative conclusions can be drawn.
d)
The temperature dependence of NQR frequencies should be investigated carefully to correct for the crystal field effect as accurately as possible.
e)
For other nuclei besides 35Cl, and 79,81Br, such as 127I, 14N,..., more experimental evidence is needed to clarify the connection between NQR and the specific interactions between molecules in the solid state and in molecular addition compounds.
22 citations
••
TL;DR: In this article, the influence of the ammonium ion dynamics on the structural stability of these crystals was discussed with special regard to the influence on the chemical properties of ammonium-ion dynamics.
Abstract: Recent and novel data obtained from chlorine NQR measurements on natural and deuterated (NH 4 ) 2 MCl 6 compounds are discussed with special regard to the influence of the ammonium-ion dynamics on the structural stability of these crystals. The temperature dependence (4.2 K to 350 K) of the chlorine NQR frequency ν Q and relaxation rates T 1 −1 , T 2 −1 obtained from the natural ammonium salts of Sn, Pd, Os, Pb, Te, Se and from the deuterated salts of Sn, Te and Se are analysed. Slight deviations from the normal temperature behaviour of ν Q and T 1 −1 are found in Sn, Pd and Os compounds which stay cubic in the whole temperature range. The ammonium compounds of Pb and Te undergo a structural transformation between 80 K and 90 K from the cubic to a trigonal phase which is distinguished by the preservation of the single line spectrum of the chlorine NQR below T c1
22 citations
•
04 Feb 2005TL;DR: In this paper, the use of two or more sensors tuned to at least two different nuclear quadrupole resonance frequencies of a target compound to detect the different NQR signals greatly reduces the chance of misidentification, and thereby improves the performance of the system.
Abstract: The use of two or more sensors tuned to at least two different nuclear quadrupole resonance frequencies of a target compound to detect the different nuclear quadrupole resonance signals greatly reduces the chance of misidentification, and thereby improves nuclear quadrupole resonance detection system performance.
22 citations