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.

Barium nuclear magnetic resonance spectroscopic study of YBa2Cu3O7.

Abstract: We have measured the 135 Ba nuclear magnetic resonance (NMR) line shape and the 137 Ba nuclear quadrupole resonance (NQR) of a powder sample of YBa 2 Cu 3 O 7 , at 300 K, as well as the temperature and field dependences of the 135,137 Ba NMR line shapes and spin-lattice relaxation rates of magnetically aligned (cH 0 ) samples, in the normal and superconducting states

Nuclear Quadrupole Resonance Studies of Charge‐Transfer Complexes of Carbon Tetrabromide with Methyl‐Substituted Benzenes and Pyridines

Abstract: The 81Br nuclear quadrupole resonance spectra have been examined for a series of complexes of CBr4 with methyl‐substituted benzenes and pyridines. The p‐xylene−CBr4 complex gives two lines as expected from the known structure, and the benzene–CBr4 spectrum is the same, with a lower splitting. The spectra of a number of other complexes of unknown structure do not correlate simply with these. Estimates of the direct crystal‐field gradients due to the charge distribution in the aromatics suggest that the direct field gradient effects are much too low to account for observed shifts in quadrupole frequencies. The temperature dependencies of the resonances in the p‐xylene and durene complexes have been studied. The p‐xylene complex follows the Bayer equation, but the durene complex requires the inclusion of a temperature dependence of the torsional frequency. Both complexes show a fading of the resonances at about 50° below the melting points.

Rapid Identification of Halogen Bonds in Co-Crystalline Powders via 127 I Nuclear Quadrupole Resonance Spectroscopy

Abstract: 127 I nuclear quadrupole resonance (NQR) spectroscopy is established as a rapid and robust method to indicate the formation of iodine-nitrogen halogen bonds in co-crystalline powders. Once the relevant spectral frequency range has been established, diagnostic 127 I NQR spectra can be acquired in seconds. The method is demonstrated for a series of co-crystals of 1,4-diiodobenzene. Changes in the 127 I quadrupolar coupling constant (CQ ) by up to 74.4 MHz correlate with the length of the C-I donor covalent bond and inversely with the I⋅⋅⋅N halogen-bond length. The predictive power of this technique is validated on two previously unknown co-crystalline powders prepared mechanochemically. Single-crystal growth via co-sublimation and structure determination by single-crystal X-ray diffraction cross-validates the findings. Natural localized molecular-orbital analyses provide insight into the origins of the quadrupolar coupling constants.