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: The information inferred from NQR study on local electron density distribution together with analysis of charge distribution, provides excellent means for determination of reactive sites and hence, can indicate possible promising directions to be followed in drugs design.
36 citations
TL;DR: In this article, 59Co NMR studies on magnetically oriented powder samples of Co oxide superconductors, NaxCoO2·yH2O, with Tc~4.7 K were carried out, and the abplane Knight shift in the normal state was estimated from the magnetic field dependence of second-order quadrupole shifts at various temperatures.
Abstract: We report 59Co NMR studies on magnetically oriented powder samples of Co oxide superconductors, NaxCoO2·yH2O, with Tc~4.7 K. From the two-dimensional powder pattern in the NMR spectrum, the ab-plane Knight shift in the normal state was estimated from the magnetic field dependence of the second-order quadrupole shifts at various temperatures. Below 50 K, the Knight shift shows a Curie–Weiss-like temperature dependence, similarly to the bulk magnetic susceptibility χ. From the analysis of the so-called K–χ plot, the spin and the orbital components of K and the positive hyperfine coupling constant were estimated. The onset temperature of the superconducting transition in the Knight shift does not change much in an applied magnetic field up to 7 T, which is consistent with the reported high upper critical field Hc2. The Knight shift at 7 T shows an invariant behaviour below Tc. No coherence peak just below Tc was observed in the temperature dependence of the nuclear spin–lattice relaxation rate 1/T1 in either case (NMR, nuclear quadrupole resonance). We conclude that the invariant behaviour of the Knight shift below Tc and unconventional behaviours of 1/T1 may indicate spin triplet superconductivity with p- or f-wave symmetry.
36 citations
TL;DR: In this paper, an infrared-radiofrequency double resonance inside a CO 2 N 2 O laser cavity has been applied to the observation of pure nuclear quadrupole resonance and direct A 1 - A 2 transitions of CH 3 Br.
36 citations
TL;DR: The nuclear quadrupole couplings of NH4ReO4 have been measured over a wide range of temperatures, showing that disappearance of the resonance is due to gradients of temperature and strain in the sample.
Abstract: The nuclear quadrupole couplings of the 187Re, 14N, and 2H nuclei in NH4ReO4 have been measured over a wide range of temperatures. The 187Re nuclear quadrupole resonance has been observed throughout the previously reported ’’wipeout’’ range of temperature, showing that disappearance of the resonance is due to gradients of temperature and strain in the sample. The pressure dependence of 187Re quadrupole resonance has been measured as a function of temperature between 77 and 362 K. The slope of the graph of (∂ν/∂P)T versus temperature is indicative of a continuous phase transition at this temperature. The nature of the phase transition and its relationship to other phenomena in NH4ReO4 is unclear.
36 citations
TL;DR: In this paper, a detailed study of the pure nuclear quadrupole resonance of 14N in solid triethylene diamine is described, and the resonance frequency, spin-lattice relaxation time, and free-induction decay time are measured as a function of temperature from 80°K to the plastic transition at 351°K.
Abstract: A detailed study of the pure nuclear quadrupole resonance of 14N in solid triethylene diamine is described. The resonance frequency, spin–lattice relaxation time (T1), and the free‐induction decay time (T2) were measured as a function of temperature from 80°K to the plastic transition at 351°K. From 200°–300°K T1 is dominated by hindered molecular rotations about the trigonal axis of the molecule modulating the dipolar interaction with the protons. The activation for this reorientation was found to be 8.17 kcal/mole, in reasonable agreement with NMR results of Smith. The linewidth is discussed in detail and indicates an acentric structure of the molecule. Effects of the approach to the plastic transition are evident in all the three quantities measured but could not be interpreted in detail.
36 citations