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.

Detection of contraband using nuclear quadrupole resonance

Abstract: This invention relates to the use of a nuclear quadrupole resonance detection system for detecting contraband, wherein the detection system comprises a container with a detection panel and at least one coil for exciting and detecting the nuclear quadrupole resonance frequencies of a contraband source placed near an outer side of the detection panel.

Copper-63 nuclear quadrupole resonance frequencies and molecular geometries of three-co-ordinate complexes of copper(I) halides with N-alkylimidazolidinethione and thiazolidinethione ligands

Abstract: The crystal structures of seven three-co-ordinated complexes of copper(I) halides with thione ligands, [CuXL2], where L = 1,3-thiazolidine-2-thione and X = Cl or Br, L =N-ethylimidazolidine-2-thione and X = Br, L =N-isopropylimidazolidine-2-thione and X = Cl or Br, and L =N-propylimidazolidine-2-thione and X = Cl or I have been determined. In all complexes, the copper lies in a trigonal-planar environment and the thiazolidine or imidazolidine rings show no major distortion from planarity. Owing to the presence of hydrogen bonding involving H[N(2)], or H[N(02)], and the halogen atom all complexes adopt a W-shaped conformation. The 63Cu NQR frequencies of these complexes, together with those of two other similar complexes whose structures were already available, depend, for a given halide, on the S–Cu–S bond angle, a decrease in angle producing an increase in resonance frequency: νCl= 28.7 – 0.544Δθ and νBr= 26.9 – 0.229Δθ MHz, where Δθ is the difference between the S–Cu–S bond angle and 120°. This behaviour has been rationalized in terms of a partial field-gradient model of the resonance frequencies.

Two-dimensional Nutation Echo Nuclear Quadrupole Resonance Spectroscopy

Abstract: Abstract We discuss two new two-dimensional nuclear quadrupole resonance experiments, both based on the principle of nutation spectroscopy, which can be used to determine the asymmetry parameter, and thus the full quadrupolar tensor, of spin-3/2 nuclei at zero applied magnetic field. The first experiment is a simple nutation pulse sequence in which the first time period (t1) is the duration of the radiofrequency exciting pulse; and the second (t2) is the normal free-precession of a quadrupolar nucleus at zero-field. After double Fourier-transformation, the result is a 2 D spectrum in which the first frequency dimension is the nutation spectrum for the quadrupolar nucleus at zero-field. For polycrystalline samples this sequence generates powder lineshapes; the position of the singularities, in these lineshapes can be used to determine the asymmetry parameters η in a very straightforward manner, η has previously only been obtainable using Zeeman perturbed NQR methods. The second sequence is the same nutation experiment with a spin-echo pulse added. The virtue of this refocussing pulse is that it allows acquisition of nutation spectra from samples with arbitrary inhomogeneous linewidth; thus, asymmetry parameters can be determined even where the quadrupolar resonance is wider than the bandwidth of the spectrometer. Experimental examples of 35Cl, 81Br and 63Cu nutation and nutation-echo spectra are presented.