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.

Explosives Detection Using Magnetic and Nuclear Resonance Techniques

Abstract: Preface.- Fundamentals of Pulsed Nitrogen-14 Quadrupole Resonance D. Canet, M. Ferrari.- 14N NQR Detection of Explosives with Hybrid Sensors M. Pannetier-Lecoeur et al.- Polarization Enhanced NQR Detection at Low Frequencies J. Luznik et al.- Efficient Excitation and Ringing Suppression in Nuclear Quadrupole Resonance J.B. Miller et al.- Detection of Concealed Liquid Explosives and Illicit Drugs in Unopened Bottles S. Kumar, P.J. Prado.- Prospectives and Limitations of NQR Signal Enhancement by Polarisation Transfer A.F. Privalov et al.- Modeling of QR Sensors for Optimized Explosives Detection H. Robert et al.- Detection of Explosives by NQR Method: Main Aspects for Transport Security T.N. Rudakov.- Double Resonance Detection of (Mainly Nitrogen) NQR Frequencies in Explosives and Drugs J. Seliger, V. Zagar.- Signal Processing Methods in NQR V.S. Grechishkin et al.- 14N Nuclear Quadrupole Resonance Signals in Paranitrotoluene and Trinitrotoluene. Spin-Lock Spin-Echo off-resonance Effects A. Gregorovic et al.- Identification of Liquids Encountered in Carry-on-Luggage by Mobile NMR J. Mauler et al.- The Two-Frequency Multipulse Sequence in Nuclear Quadrupole Resonance of N-14 Nuclei G.V. Mozzhukhin et al.- The Detection of Industrial Explosives by the Quadrupole Resonance Method: Some Aspects of the Detection of Ammonium Nitrate and Trinitrotoluene G.V. Mozzhukhin et al.- Development of Electric Field NMR Signal Acquisition System R.J. Prance et al.- Berry's Phase in NQR of Powders N. Sinyavsky et al.- Contribution of Copper NQR Spectroscopy to the Geological Studies of Complex Sulfides and Oxides R.R. Gainov et al.- Index.-

NMR Study on Spin Gap in Spin Ladder Sr14Cu24O41

Abstract: We have investigated spin dynamics of both the ladder and the chain sites in Sr 14 Cu 24 O 41 by Cu-NMR and Cu-NQR. From the NMR shift, K spin , and nuclear spin-lattice relaxation time, T 1 , the energy gaps in the spin excitation spectrum are confirmed to be Δ=140 K for the chain site and Δ=470 K for the ladder site for Sr 14 Cu 24 O 41 . Doping effects on the spin gaps and electric field gradient at the Cu sites were also investigated by the substituting of Ca, Y and La for Sr. The spin gap of the ladder site decreases with increasing x for Sr 14- x Ca x Cu 24 O 41 and seems to collapse at around x =13 for Ca substitution.

Computational studies on boron nitride and boron phosphide nanotubes: Density functional calculations of boron-11 electric field gradient tensors

Abstract: We have performed density functional theory (DFT) calculations employing BLYP exchange functional and 6–31 G * standard basis set by GAUSSIAN 98 package of program The electronic structure properties of representative zigzag and armchair models of boron nitride nanotube (BNNT) and boron phosphide nanotube (BPNT) have been studied The (6,0) and (4,4) structures have been optimized and the electric field gradient (EFG) tensors have been calculated at the sites of various boron-11 nuclei The calculated EFG tensors have been converted to the equivalent experimental nuclear quadrupole resonance (NQR) parameters, quadrupole coupling constant and asymmetry parameter The results revealed that the boron atoms at the edges of nanotubes play dominant roles in determining the electronic behaviors of BNNT and BPNT The average of the calculated values of quadrupole coupling constants at the sites of boron-11 nuclei is in good agreement with experiments

Atom movement in In3La studied via nuclear quadrupole relaxation.

Abstract: Jump frequencies of Cd tracer atoms in In3La were measured via nuclear quadrupole relaxation caused by stochastic reorientation of the electric field gradient using the method of perturbed angular correlation of gamma rays. Activation enthalpies of 0.53(1) and 0.81(1) eV were found at the two phase boundaries, which differ in composition by only about 0.1 at. %. The jump frequency was found to be higher at the more In-rich phase boundary, ruling out a simple In-vacancy diffusion mechanism. Possible diffusion mechanisms and general applicability of the method are discussed.

Nuclear Quadrupole Resonance for Explosive Detection

Abstract: A nuclear quadrupole resonance (NQR) detector has been developed. This detector targets to cyclotrimethylenetrinitramine (RDX), a high explosive inside an antipersonnel landmine, which are buried up to 15 cm deep. This detector works well outside an electromagnetically shielded room. It was also mounted on an anti-mine vehicle and remotely controlled mine detection was demonstrated in public.