Energy Transport by Cascade and Resonance Processes in Doubly Activated Phosphors

A method, using quantum efficiency measurements, is described for obtaining the efficiency of energy transfer from sensitizer to activator centers in doubly activated phosphors when both centers have allowed transitions. From these measurements and applying the theory of resonant transfer it is concluded that, for , Cu, both cascade and resonant transfer mechanisms are important and that the resonant transfer process increases more rapidly with concentration than does the cascade process.