Factors affecting the quantum efficiencies of fluorescent terbium(III) chelates in the solid state

Abstract

Investigations of tris- and tetrakis-hexafluoroacetylacetonato- and trifluoroacetylacetonato-terbium(III) complexes have established that the temperature-dependence of the ⁵D₄ lifetime is caused by thermal depopulation of the ion level to a ligand triplet state. Ligand triplet to ground state deactivation rates, A, have been determined and range from 10⁴ to 10⁷ s^–1. Neither variation in thermal depopulation rates nor A is sufficient to explain the observed differences in quantum efficiencies and it is suggested that significant losses may occur before the triplet state in the energy transfer process.