Decay Modes with Coherent Resonant-Energy Transfer between Deep Impurities in Solids

Abstract

Attention is called to the existence of new decay modes for deep impurities in solids associated with coherence in the resonant-energy transfer between them. The theoretical decay rate $R$ of the two-impurity complex is of the form $R\left(t\right)=C_1\exp (-{\gamma }_{1}t)+C_2\exp (-{\gamma }_{2}t)+\exp [-\frac{1}{2}({\gamma }_1+{\gamma }_2\left)t\right]\times \mathrm{Re}D\exp (-i\Delta t)$, with $C_n$, ${\gamma }_n$ real positive, $\Delta$ real, and $D$ complex. The oscillations in time $t$ exhibited by the third term in the expression for $R$ provide an experimental test for the coherence effect. The partial rate $R_{\nu }\mathrm{}\left(t\right)\mathrm{}$ for radiative decay is of the same form as the total rate $R\left(t\right)\mathrm{}$. In the analysis, use is made of an analogy between the decay of the excited impurity complex and that of $K^0$ mesons in particle physics, where similar coherent oscillations have been observed experimentally.