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.

Order-disorder effects of small guests in clathrates studied by nuclear quadrupole resonance and crystallography. Part I. Carbon tetrachloride and related molecules in Ni(SCN) 2 (3-methylpyridine) 4

Abstract: NQR spectroscopy and X-ray crystallography have been jointly applied to the study of the small guest molecules CH2Cl2, CHCl3, CCl4, CBr2Cl2, C(CH3)2Cl2 etc. in the Werner host complex Ni(SCN)2(3-methylpyridine)4. Specific host-guest dipole-dipole interactions play an important role in order-disorder effects for guest molecules in the cavities of orthorhombic system,Fddd. Thus a weakly polar molecule such as CBr2Cl2 exhibits a disordered alternation, both the bromine and the chlorine atoms occupying the two possible sites in theC2 cavity, whereas for the polar molecule C(CH3)2Cl2, an ordered structure is observed. In addition, two new types of crystal structures,C2/c andP\(\bar 1\), are reported here for dichloromethane and chloroform clathrates.

75As-NMR Studies of LaFeAsO1-xFx for Various x Values

Abstract: Results of 75 As NMR and NQR measurements are reported for superconducting samples of LaFeAsO 1- x F x with various x values. The x dependent widths of the superconducting transition and those of the NQR spectra indicate that the optimally doped LaFeAsO 1- x F x sample with the superconducting transition temperature T c ∼28 K has the smallest width or smallest inhomogeneity of the superconducting order parameter Δ. In the analyses of the temperature ( T ) dependence of the NMR longitudinal relaxation rate 1/ T 1 , we have tried to use a simple relation 1/ T 1 ∼ T n to see how fast 1/ T 1 decreases when the superconducting order parameter grows. The relation holds rather well in the T region of ∼0.3 T c < T ≤ T c , and n varies from 2.5–6 with varying x , having the maximum value 5–6 at the optimal x . These results indicate that the x dependence of n originates from the spatial distribution of Δ, and that the T 5–6 behavior is considered to be intrinsic to this system.

Effects of charge inhomogeneities on elementary excitations in La 2 − x Sr x CuO 4

Abstract: Purely local experimental probes of many copper oxide superconductors show that their electronic states are inhomogeneous in real space. For example, scanning tunneling spectroscopic imaging shows strong variations in real space, and according to nuclear quadrupole resonance (NQR) studies, the charge distribution in the bulk varies on the nanoscale. However, the analysis of the experimental results utilizing spatially averaged probes often ignores this fact. We have performed a detailed investigation of the doping dependence of the energy and linewidth of the zone-boundary Cu-O bond-stretching vibration in ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4}$ by inelastic neutron scattering. Both our results as well as previously reported angle-dependent momentum widths of the electronic spectral function detected by angle-resolved photoemission can be reproduced by including the same distribution of local environments extracted from the NQR analysis.