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.
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TL;DR: The nuclear quadrupole resonance in metallic indium has been followed continuously from 4.2 to 390.2 K and two sources of field gradient have been investigated as mentioned in this paper, one of which is the usual "ionic" model involving point ions in a uniform background charge density.
Abstract: The nuclear quadrupole resonance in metallic indium has been followed continuously from 4.2\ifmmode^\circ\else\textdegree\fi{}K to 390.2\ifmmode^\circ\else\textdegree\fi{}K and two sources of field gradient have been investigated. One of these is the usual "ionic" model involving point ions in a uniform background charge density. The contribution from this source has been calculated by a new method to seven figures at three representative $\frac{a}{c}$ ratios; from these data the ionic field gradient in indium at any submelting temperature can be inferred.Since the ionic contribution accounts for only about 20% of the observed field gradient, a second source has been considered. This source is an undulatory component of charge density having the periodicity of the lattice. It is found that a modest amount of this undulatory component does produce sufficient field gradient to explain the observations.
49 citations
TL;DR: In this paper, a pressure-dependent zero-field 63Cu nuclear quadrupole resonance frequency corresponding to the transition in Cu2O was measured in cylinder-piston type chambers with an accuracy of ∼100 bar.
Abstract: We present a manometer designed to measure pressures of 1–20 kbar in temperatures between 4–300 K in cylinder‐piston type chambers, with an accuracy of ∼100 bar. The manometer is based on pressure‐dependent zero‐field 63Cu nuclear quadrupole resonance frequency corresponding to ‖±3/2〉↔‖±1/2〉 transition in Cu2O. The nuclear quadrupole resonance frequency νQ varies linearly with pressure and its temperature dependence is adequately explained by a model of lattice vibrational modes in O—Cu—O bonds. This manometer is particularly convenient for zero or high‐field magnetic resonance experiments.
49 citations
TL;DR: In this paper, the authors give solutions for spin-lattice relaxation in NQR due to magnetic interactions, generalized for non-axial crystal fields with eta not=0.
Abstract: The authors give solutions for spin-lattice relaxation in NQR due to magnetic interactions, generalized for non-axial crystal fields with eta not=0. They find analytic expressions for I=3/2 and give numerical solutions for I=5/2, 7/2 and 9/2. They find that the relaxation curves change considerably with eta . Specific results are derived for relaxation due to Fermi contact in metals and other electronic hyperfine interactions. They also describe changes induced by the addition of a magnetic field, indicating fields at which standard NMR results break down.
49 citations
07 Oct 1996
TL;DR: Nuclear quadrupole resonance (NQR) has been used for mine detection as discussed by the authors, which relies on the observation of radiofrequency (RF) signals from the /sup 14/N nuclei present in the explosive.
Abstract: Nuclear quadrupole resonance (NQR) methods of mine detection rely on the observation of radiofrequency (RF) signals from the /sup 14/N nuclei present in the explosive The frequencies of these signals lie between 05 and 6 MHz; they are characteristic of a given explosive and provide not only a positive identification but also an estimate of quantity or depth Unlike the better known technique of nuclear magnetic resonance (NMR), no static magnetic field is needed, so that portable probes can be used Furthermore, signals are only seen in solids or solid-like materials, and because of the highly compound-specific nature of NQR frequencies, there is little, if any interference from other nitrogen-containing materials which may be present in the mine casing or the surrounding terrain The paper discusses the principles of NQR and experimental methods, and its application to mine detection
48 citations
TL;DR: In this paper, a simple continuum theory for quadrupole relaxation rates of ions in polar solvents is presented, and the surprising success of the relatively crude continuum model is discussed and the implications for molecular theories of quadrupoles relaxation are indicated.
Abstract: A simple continuum theory for quadrupole relaxation rates of ions in polar solvents is presented. The predicted rates agree fairly well with experimental rates determined for various ions in several solvents. The surprising success of the relatively crude continuum model is discussed and the implications for molecular theories of quadrupole relaxation are indicated.
48 citations