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.

Landmine Detection by Nuclear Quadrupole Resonance (NQR)

Abstract: Nuclear Quadrupole Resonance (NQR) combines the compound specific detection capability offered by chemical detection techniques with the spatial localization capability and convenience of an induction coil metal detector. In the 16 years since NQR was last applied to mine detection in the U.S., there has been considerable improvement in the basic techniques. This paper reviews the progress achieved under a recent initiative to detect landmines by NQR. Two basic technical developments are summarized: the design of a detection coil suitable for probing the ground for landmines buried at typical depths, and an increase in the NQR signal obtained from the explosive TNT. In addition, we report the sensitivity of an NQR detection system to detect the electromagnetic response of metal-cased landmines.

Zero-Field Nuclear Quadrupole Spin-Lattice Relaxation in the Rotating Frame

Abstract: Nuclear quadrupole spin-lattice relaxation rates in different frames of reference for pure electric quadrupole coupling are evaluated in terms of spectral density functions of lattice vibrations. The rate is determined in each of three important reference frames defined with respect to (1) the axial crystalline field in the laboratory, (2) a strong rotating radiofrequency field, and (3) internal dipolar fields following adiabatic demagnetization in the rotating frame. For spin states established by pure quadrupole coupling, modification of the relaxation behavior in the different frames does not conform to the behavior obtained from spins bound in pure magnetic Zeeman states. The density-matrix perturbation formalism is applied. In order to transform the total Hamiltonian into the interaction representation of the main quadrupole interaction, a convenient representation is devised for quadratic exponential unitary operators which do not directly carry out simple rotations. The transformation permits an approach to the rigorous analysis of dynamic nuclear quadrupole resonance phenomena which usually have been qualitatively described by comparison with analogous phenomena in pure magnetic resonance. The new representation is presented explicitly for spin $I=\frac{3}{2}$. Experimental measurements of ${\mathrm{Cl}}^{35}$ pure quadrupole spin-lattice relaxation times in chlorate salts in the three reference frames are compared with the theoretically determined relaxation rates.

Nuclear Quadrupole Resonance Detection of Explosives

Abstract: Publisher Summary This chapter gives the account of the detection of explosive devices. The detection can be classified into two schemes — ”seeing” the device and detecting a certain component which is common to all devices. X-ray imaging is a model example of the previous scheme. It gives an image of the contents of anitem under inspection. It is presented upon the operator to be acquainted with the explosive device. Metal detection is a very good example of the latter scheme. Almost all land mines contain no less than a little quantity of metal that can be detected through a metal detector. Evidently, many guiltless objects contain metal. The problem is separating the guiltless from the hazardous. To detect the explosive device without any hesitation is to detect it with the help of devices. The thermal neutron analysis and dual-energy X-ray give the specificity and issues of radiation, which can be challenging in some situations. This chapter discusses the nuclear quadrupole resonance (NQR). NQR stimulates and detects the radio frequency (RF) signals from certain nuclei in molecules of interest and are called explosives.