Perturbed-angular-correlation measurement of motional-correlation time in liquid Se

Abstract

The motional-correlation time ${\tau }_m$ of very dilute Cd impurities in liquid Se was found by measuring the perturbed-angular-correlation of $\gamma$ rays from ${}_{}{}^{111}{}_{}{}^{}\mathrm{Cd}$ following the decay of ${}_{}{}^{111}{}_{}{}^{}\mathrm{In}$. The measured correlation time varies from 2 × ${10}^{-10\mathrm{}}$ sec at 500°C to 2 × ${10}^{-11\mathrm{}}$ sec at 900°C. From 500 to 800°C ${\tau }_m\propto \exp \left(\frac{E_m}{\mathrm{kT}}\right)$ where $E_m=0.36\mathrm{}$ eV (8.3 kcal/mole). It is shown that the ${\tau }_m$ thus measured represents a lower limit for the Se-Se and Se-Cd bond lifetimes.