Localized excitation transfer processes in MgO:Cr 3+

Abstract

Site selective laser spectroscopy and transient grating studies have been used to investigate energy transfer from (Cr . Mg) donors to Cr 3+ acceptors in tetragonal and orthorhombic sites. The results are consistent with energy transfer between all donor-acceptor pairs. However, the energy transfer to the N 3-acceptor only occurs from distinct, slightly perturbed (Cr . Mg) centres. The transient grating experiments show that at high concentration spatial energy migration does occur but only with very small diffusion constants. In general, excitation migration is strongly localized in these materials.