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.

Multigap superconductivity in locally noncentrosymmetric SrPtAs: An As 75 nuclear quadrupole resonance investigation

Abstract: We report detailed $^{75}\mathrm{As}$ nuclear quadrupole resonance investigations of the locally noncentrosymmetric superconductor SrPtAs. The spin-lattice relaxation studies prove weakly coupled multigap superconductivity. A retardation of the decay in $1/{T}_{1}T$ evidences a nodeless (fully gapped) superconducting state on the complex multipocket Fermi surface, which is consistent with an anisotropic $s$-wave order parameter and with proposed unconventional $f$-wave and chiral $d$-wave symmetries. A quantitative analysis of these models favors the unconventional $f$-wave state.

14N nuclear quadrupole resonance in compounds containing N–O bonds. I. Oximes

Abstract: The 14N nuclear quadrupole resonance spectra at 77°K of several hydrazines are reported and analyzed in the framework of a semiempirical theory extended to cover cases of large asymmetry parameters. The atomic‐orbital occupation numbers obtained by this analysis are linked with the hydrogen‐bonding configuration in the solid state. The results obtained indicate that the hydrogen bonding ability of the amino nitrogen exceeds that of the substituted nitrogen atom and decreases in the order: hydrazine>alkyl hydrazines>N‐amino heterocycles>aryl hydrazines.

Analysis of the Electric Field Gradients and the Knight Shifts at All Cu and O Nuclei in YBa2Cu3O7

Abstract: Electronic configurations and local susceptibilities at all copper and oxygen sites in YBa 2 Cu 3 O 7 are determined from the analysis of the electric field gradients (EFG's) and the Knight shifts (shifts). Besides main contributions from 3 d holes for Cu sites and 2 p σ holes for O sites, it is necessary to consider 4 p electrons of Cu and 2 p π holes of O for accurate analysis of the EFG's, and 4 s electrons of Cu and 2 s holes of O for the shifts. Difference in the observed EFG's between Cu(1) and Cu(2) is due to the 4 p -electron contributions, and the 3 d -electron states are determined to be quite similar. Each site of Cu and O shares almost same amount of holes. The local spin susceptibilities, however, are fairly different in order of magnitude as Cu(2), Cu(1), O(2, 3), O(4), implying a strong correlation in Cu(2).

Coordination of Cu(II) to Lipophilic Bis-hydroxamate Binders As Studied by One- and Two-Dimensional Electron Spin Echo Spectroscopy

Abstract: The binding of Cu(II) to a lipophilic bis-hydroxamate binder, RL252, and its parent RL239, was investigated by pulsed EPR. The binders have two arms, each terminated with a hydroxamate group which serves as a donor. The major difference between RL252 an RL239 is the absence of the leucine amino acid bridge in RL239. Orientation-selective electron spin echo envelope modulation (ESEEM) experiments were carried out at 8.45 and 9.15 GHz. The spectra obtained were exceptionally well resolved and indicated that the cancellation condition, which requires that the hyperfine coupling is approximately twice the nuclear Larmor frequency, is met at 8-9 GHz. The spectra of both Cu-RL252 and Cu-RL239 showed the nuclear quadrupole resonance (NQR) frequencies, v{sub o}, v{sub -}, and v{sub +}, of the {sup 14}N of the hydroxamate groups at 1.6-1.7, 2.15-2.25, and 3.8-3.9 MHz. A peak corresponding to the double quantum transition in the `noncanceled manifold` v{sub DQ}, was observed at 5-5.2 MHz, and at some magnetic fields a peak corresponding to a single quantum transition, v{sub SQ}, and its combination harmonic appeared as well. The assignment of all the ESEEM frequencies was achieved by the application of the two-dimensional hyperfine sublevel correlation (HYSCORE) experiment. Following the assignment, simulationsmore » of the orientation-selective ESEEM spectra were performed, yielding the magnitude and orientation of the quadrupole and hyperfine tensors of the coupled nitrogens. 52 refs., 9 figs., 3 tabs.« less