Nuclear magnetic resonance of K2 in optically pumped potassium vapor

Rui Zhang, Zhiguo Wang, Xianghe Peng +3 more

R. Gupta, W. Happer, George Moe +1 more

NMR signals from diatomic alkali molecules have been observed in optically pumped cesium and rubidium vapors. The nuclear relaxation times were found to be strongly dependent on the temperature and buffer-gas pressure. The relaxation time seems to be determined by at least two and possibly three major factors: motional narrowing of the molecular hyperfine structure, breakup of the diatomic molecules by collisions with buffer-gas atoms, and possibly chemical exchange of free atoms with atoms bound in the molecules.

M. E. Movsesyan, N. N. Badalyan, V. A. Iradyan

Zhiguo Wang, Jiajia Li, Zhiqiang Xiong

In order to investigate the influence of pump beam truncation on the transverse relaxation time of 129Xe nuclear spins in a nuclear magnetic resonance gyroscope, we measured the transverse relaxation rate as a function of pump laser power and vapor cell temperature for two ovens with different optical access sizes. The experimental results conform qualitatively to a theoretical model based on magnetic field gradient induced by polarization gradient of Rb atoms. It is found that the non-uniform power distribution in the beam cross-section led to remarkable relaxation, especially for the 129Xe nuclear spins in a large-size vapor cell. To reduce the polarization gradient, the spatial distribution of the pump laser power in the cell should be as homogenous as possible. These results are of significance to the design of a high precision nuclear magnetic resonance gyroscope.

J. Rud Nielsen

Chuanming Yin, Xiangyang Zhou, Weiqian Wang +6 more

This paper presents a pump-light-based in-situ temperature measurement method for nuclear magnetic resonance (NMR) vapor cells under oblique optical incidence. To miniaturize the NMR sensor, a thin vapor cell is employed, in which both the orthogonal pump and probe light are introduced obliquely through one surface of the vapor cell. A model is developed to relate pump-light absorption to Rb atomic density, thereby enabling inference of the vapor cell temperature. The model includes polarization distortion, polarization-dependent window transmission attenuation, effective optical path length, and the coupling between optical absorption and atomic polarization. Experimental results show that the proposed method achieves the lowest RMSE of 0.179 K and reduces it by at least 68.2% compared with several commonly used fitting methods, enabling accurate in-situ temperature measurement in miniaturized NMR sensors under obliquely incident pumping.