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.

Observation of Antiferromagnetic Nuclear Resonance of Cu in YBa2Cu3O6

Abstract: The zero-field antiferromagnetic nuclear resonance (AFNR) of Cu in the high- T c related oxide YBa 2 Cu 3 O 6 has been observed at 89.89±0.05 MHz for 63 Cu and 96.29±0.05 MHz for 65 Cu with well articulated quadrupole splittings at 1.3 K. These frequencies correspond to a hyperfine field of 79.65±0.05 KOe. From the analysis of the AFNR spectrum and the observation of NQR at 30.11±0.2 MHz for 65 Cu and 27.88±0.02 MHz for 63 Cu, both of which have no Zeeman splitting, it is concluded that the antiferromagnetic mounents reside only on the CuO 2 plane sites and the direction of moments is perpendicular to the c -axis. This is consistent with the spin structure proposed by neutron diffraction studies. The nuclear relaxation behavior is also discussed briefly.

Nuclear Quadrupole Resonance

Abstract: Nuclear quadrupole resonance is a recently developed branch of radio-frequency spectroscopy which is concerned with magnetic resonance absorption in crystals. This absorption is due to reorientation of the nonspherical atomic nuclei against crystalline electric fields. Related phenomena in isolated molecules are briefly mentioned in the Introduction A. This is followed in Sec. B by an elementary treatment of the electrostatic interaction of a nonspherical nucleus with an axially symmetric inhomogeneous electric field as is found approximately in crystalline Cl2, a crystal whose structural units are very nearly undisturbed Cl2 molecules. Electrostatic torques are shown to exist which cause a precession of the nuclear angular momenta around the molecular axes. As this motion is accompanied by a precession of the magnetic and electric moments of the nuclei, which may interact with alternating electromagnetic fields, this leads over to the transition mechanism between the energy levels which are obtained from...

$s$-wave superconductivity in kagome metal CsV$_{3}$Sb$_{5}$ revealed by $^{121/123}$Sb NQR and $^{51}$V NMR measurements

Abstract: We report $^{121/123}$Sb nuclear quadrupole resonance (NQR) and $^{51}$V nuclear magnetic resonance (NMR) measurements on kagome metal CsV$_3$Sb$_5$ with $T_{\rm c}=2.5$ K. Both $^{51}$V NMR spectra and $^{121/123}$Sb NQR spectra split after a charge density wave (CDW) transition, which demonstrates a commensurate CDW state. The coexistence of the high temperature phase and the CDW phase between $91$ K and $94$ K manifests that it is a first order phase transition. At low temperature, electric-field-gradient fluctuations diminish and magnetic fluctuations become dominant. Superconductivity emerges in the charge order state. Knight shift decreases and $1/T_{1}T$ shows a Hebel--Slichter coherence peak just below $T_{\rm c}$, indicating that CsV$_3$Sb$_5$ is an s-wave superconductor.

Detection of explosive and narcotics by low power large sample volume nuclear quadrupole resonance (NQR)

Abstract: The sensitive detection of explosives and narcotics by nuclear quadrupole resonance (NQR) is performed at low rf power by assuring that the rf field strength is larger than the local magnetic field. Additionally, it has been recognized that signal-to-noise ratio of a signal induced by a specimen of fixed size decreases by only the square root of the coil size. Thus, rather than scaling power linearly with coil size, as conventionally done to maintain the same rf field intensity, the power needs only be increased by the square root of the increased coil size to assure maintenance of the same signal to noise ratio. This technique permits the use of larger coils than previously used. The invention is useful for both volume coils and surface coils.