Luminescence kinetics and emission lifetime distribution of Cr 3+-doped aluminosilicate glass

Abstract

Luminescence decay measurements of Cr 3+ ions in an aluminosilicate glass have been recorded for different combinations of excitation wavelength, emission wavelength and temperature. The luminescence lifetime distribution has been obtained using the exponential series method and modelled by considering 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 the distribution of the intrinsic radiative lifetimes to be determined. From these data, it is determined that the main factors that influence the inhomogeneous broadening of the absorption and emission spectra, the strength of the crystal field and the magnitude of even parity distortions, are only weakly correlated with the magnitude of the odd parity distortions that principally determine radiative lifetime. A model of the temperature dependence of the luminescence lifetime distribution provides an estimate of the distribution of the energy barrier for the non-radiative processes in this system. The results of this fit show that a significant contribution to barrier crossing comes from tunnelling and that the Cr 3+ potential wells must be represented by confinement potentials rather than simple harmonic approximations.