Diffusion of Kr Isotopes in Solid Ar

The diffusion coefficient $D={D}^{0}{e}^{\ensuremath{-}\frac{{Q}^{0}}{\mathrm{RT}}}$ and isotope effect for ${\mathrm{Kr}}^{78}$ and ${\mathrm{Kr}}^{86}$ in solid Ar have been measured using a tracer technique. The activation energy $Q_{\mathrm{Kr}}^{}{}_{}{}^{0}$ depends on the interchange parameter $w$, but is estimated to lie in the range 3500-3900 cal ${\mathrm{mole}}^{\ensuremath{-}1}$, with the most reliable $w$ giving the lower value. Thus, the two calculated $Q_{\mathrm{Kr}}^{}{}_{}{}^{0