Nuclear relaxation of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ in the presence of ${\mathrm{O}}_2$

We have measured the longitudinal nuclear relaxation rate ${\mathit{T}}_1^{\mathrm{-}1}$ for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ in the presence of molecular oxygen in the temperature range T≊200–400 K. At room temperature, ${\mathit{T}}_1^{\mathrm{-}1}$=0.448±0.010 ${\mathrm{s}}^{\mathrm{-}1}$ per amagat ${\mathrm{O}}_2$, in approximate agreement with theoretical models for intermolecular dipolar relaxation. Furthermore, in this temperature range, ${\mathit{T}}_1^{\mathrm{-}1}$∝${\mathit{T}}^{\mathrm{-}0.42\pm 0.04}$. Our results are of practical importance for the growing number of applications involving hyperpolarized noble gases.