Luminescence kinetics and emission lifetime distribution of Cr3+ -doped aluminosilicate glass

Luminescence decay measurements of Cr3+ ions in an aluminosilicate glass ha ve been recorded for different combinations of excitation wavelength, emiss ion wavelength and temperature. The luminescence lifetime distribution has been obtained using the exponential series method and modelled by consideri ng the radiative lifetime distribution in the sample and the effect of non- radiative internal conversion. At low temperatures the luminescence decays are little affected by changes in experimental parameters and this allows t he distribution of the intrinsic radiative lifetimes to be determined. From these data it is determined that the main factors that influence the inhom ogeneous broadening of the absorption and emission spectra, the strength of the crystal field and the magnitude of even parity distortions, are only w eakly correlated with the magnitude of the odd parity distortions that prin cipally determine radiative lifetime. A model of the temperature dependence of the luminescence lifetime distribution provides an estimate of the dist ribution of the energy barrier for the non-radiative processes in this syst em. The results of this fit show that a significant contribution to barrier crossing comes from tunnelling and that the Cr3+ potential wells must be r epresented by confinement potentials rather than simple harmonic approximat ions. (C) 2001 Elsevier Science B.V. All rights reserved.