Polarization ofNe21by Spin Exchange with Optically Pumped Rb Vapor

We report investigations of spin exchange between ${}_{}{}^{21}{}_{}{}^{}\mathrm{Ne}$ nuclei and optically pumped Rb vapor. Polarization of 30% ($〈K_z〉=0.46\mathrm{}$) of 2×${10}^{19}$ atoms-${\mathrm{cm}}^{-3\mathrm{}}$ has been achieved with a vapor pressure of 3×${10}^{14}$ atoms-${\mathrm{cm}}^{-3\mathrm{}}$ of Rb. This high density of alkali metal can be efficiently optically pumped only when light trapping is suppressed by inclusion of at least 100 Torr of ${\mathrm{N}}_2$. In addition, we have made the first accurate measurement of the binary-collision spin-exchange rate: $〈{\sigma }_{\mathrm{ex}}v〉=(4.66\mathrm{}\pm 0.28)\times {10}^{-19\mathrm{}}$ ${\mathrm{cm}}^3$-${\mathrm{s}}^{-1\mathrm{}}$. Extension of these techniques to ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ has yielded 5% polarization of 2×${10}^{19}$ atoms-${\mathrm{cm}}^{-3\mathrm{}}$ in a preliminary experiment.