Measuring the spin polarization of alkali-metal atoms using nuclear magnetic resonance frequency shifts of noble gases

We report a novel method of measuring the spin polarization of alkali-metal atoms by detecting the NMR frequency shifts of noble gases. We calculated the profile of ⁸⁷Rb D1 line absorption cross sections. We then measured the absorption profile of the sample cell, from which we calculated the ⁸⁷Rb number densities at different temperatures. Then we measured the frequency shifts resulted from the spin polarization of the ⁸⁷Rb atoms and calculated its polarization degrees at different temperatures. The behavior of frequency shifts versus temperature in experiment was consistent with theoretical calculation, which may be used as compensative signal for the NMRG closed-loop control system