Author(s): Wang, ZG (Wang, Zhiguo); Yuan, BL (Yuan, Baolun); Zhao, HC (Zhao, Hongchang); Chen, M (Chen, Miao); Zhan, X (Zhan, Xiang); Luo, H (Luo, Hui)

Source: JOURNAL OF MAGNETIC RESONANCE Volume: 326 Article Number: 106959 DOI: 10.1016/j.jmr.2021.106959 Published: MAY 2021

Abstract: A Xe-131 nuclear magnetic resonance (NMR) oscillator can be used in the measurement of rotation rates, CPT and Lorentz violation tests, etc. To improve the measurement precision of devices based on a Xe-131 NMR oscillator, its characteristics need to be fully understood. Under the conditions where the Zeeman interaction is much larger than the quadrupolar interaction, the characteristics of the Xe-131 NMR oscillator involving the magnetic resonance, free induction decay, and closed-loop oscillation are investigated both experimentally and theoretically. The main findings are as follows. The Xe-131 NMR oscillator consists of six oscillators, three of which can be directly observed by a magnetometer. When the polarization of the Xe-131 spin ensemble can be described by a spin temperature, the ensemble exhibits both spin orientation and spin alignment. The spin alignment breaks the symmetry of the three main oscillators. The free induction decay signal of Xe-131 depends on parameters such as the spin alignment and the driving magnetic field, which make the measurement of the relaxation time difficult. In the closed-loop mode under self-excitation, the Xe-131 NMR oscillator may oscillate with more than one frequency at certain feedback gain and phase. If the quadrupole splitting is much smaller than the spin relaxation rate, then the Xe-131 oscillator can be described by the Bloch equations, and the Xe-131 oscillator will have a large amplitude. The oscillation frequency of the closed-loop oscillator depends on the quadrupole splitting, polarization, and various relaxation times, which should be considered in designing a high-precision NMR sensor. The results are significant for optimizing and improving the performance of the Xe-131 NMR oscillator as a sensor for precision measurement. (C) 2021 Elsevier Inc. All rights reserved.

Accession Number: WOS:000644070400007

PubMed ID: 33711752

ISSN: 1090-7807

eISSN: 1096-0856

Full Text: https://www.sciencedirect.com/science/article/pii/S1090780721000483?via%3Dihub