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.

17O NMR study of local hole density and spin dynamics in YBa2Cu4O8

Abstract: 17 O NMR has been carried out in YBa 2 Cu 4 O 8 with T c = 74 K. The nuclear quadrupole tensors in the oxygen sites were determined and compared with those in other high- T c cuprates. The hole densities in the oxygen and copper sites have been extracted from ν z (O) and ν Q (Cu) by assuming that the electric field gradient is dominated by the on-site holes. We propose that the hole distribution (the extent of covalency) between the planar oxygens and copper, which is changed by doping and pressure, is a hidden parameter determining the spin dynamics and the superconducting transition temperature T c in high- T c cuprates. It was found that 1/ T 1 T and the Knight shift of the planar oxygens decrease with lowering temperature in the normal state. The nuclear relaxation rates of 17 O and 63 Cu in the CuO 2 plane exhibit different behaviors at temperatures higher than ∼ 120 K, reflecting the different q -window of spin fluctuations, while both of them share the same T -dependence below ∼ 120 K down to 55 K. This scaling of 1/ T 1 between 17 O and 63 Cu, which is also seen in YBa 2 Cu 3 O 7 ( T c = 92 K) and YBa 2 Cu 3 O 6.63 ( T c = 60 K), seems to be essential for high- T c superconductivity.

35 Cl nuclear quadrupole resonance and infrared studies of hydrogen-bonded adducts of 2-chloro-4-nitrobenzoic acid

Abstract: 35 Cl nuclear quadrupole resonance and infrared spectra of solid hydrogen-bonded adducts of 2-chloro-4-nitrobenzoic acid have been studied in relation to the variation of the ΔpKa value from –2.22 to 9.04. Both methods yield the same critical value of ΔpKa equal to 3.6–3.7, which corresponds to the lowest value of the position of the centre of gravity of the i.r. protonic vibrational band and the stepwise change of 35Cl n.q.r. frequency.

Nuclear quadrupole resonance (NQR) method and probe for generating RF magnetic fields in different directions to distinguish NQR from acoustic ringing induced in a sample

Abstract: A nuclear quadrupole resonance (NQR) method and probe for generating RF magnetic fields in different directions to distinguish NQR from acoustic ringing induced in a sample. Generally, an RF magnetic field is generated along an axis towards a sample to induce a resonance signal in the sample. The resonance signal includes NQR and acoustic ringing. The resonance signal is detected along the RF magnetic field axis. The acoustic ringing is detected along a direction orthogonal to the RF magnetic field axis. As a result, the NQR in the resonance signal can be distinguished from the acoustic ringing in the resonance signal.