Diffusion limited energy transfer from Tb 3+ → Ho 3+ in calibo glass

Abstract

Non-radiative energy transfer from optically excited Tb 3+ to Ho 3+ has been studied in calibo glass. An experimental investigation has been made into the nature of the decay of excited Tb 3+ donors in the presence of Ho 3+. The time dependence of luminescence decay following pulsed excitation illustrates the transient fluorescence behaviour characteristic of diffusion-limited relaxation. The data are analysed to determine the probality for Tb 3+ to Ho 3+ energy transfer, and the critical transfer distance for energy exchange. The results imply that the mechanism of donor-acceptor energy transfer is based on electric dipole-dipole interaction. An investigation is also carried out at 80 K on excitation decay whose probability changes suddenly and in a non-correlated manner as a result of migration over randomly distributed centers, that interact with each other more strongly that they do with the acceptors.