Atomic test of the Stokes-Einstein law: Diffusion and solubility of Xe

The diffusion coefficient $D$ and the Ostwald solubility $\alpha$ have been measured for ${}_{}{}^{133}{}_{}{}^{}\mathrm{Xe}$ atoms in water-sucrose solutions ranging in viscosity $\eta$ from 1 to 289 cP, i.e., 0.68% sucrose by weight. In water $D\left(20\mathrm{}°\mathrm{C}\right)=(1.32\mathrm{}\pm 0.05)\times {10}^{-5\mathrm{}}$ ${\mathrm{cm}}^2$/sec, in agreement with the Stokes-Einstein (SE) law. Over the entire range studied the observed dependence is $D\propto {\eta }^{-0.63\mathrm{}\pm 0.02}$, significantly departing from the SE law. In water $\alpha \left(20\mathrm{}°\mathrm{C}\right)=0.108\mathrm{}\pm 0.005$. For water-sucrose solutions $\alpha$ is approximately proportional to the volume fraction of water in solution.