Spectroscopy of Cr4+ in MgCaBa aluminate glass. The coupling of 3T2 and 1E states

The spectroscopic properties of Cr4+ in MgCaBa aluminate glass at 15 K have been studied using time-resolved fluorescence measurements. It is found that the luminescence of Cr4+ in the glass is from Cr4+ ions in both high and low crystalline field sites. With increasing delays the broadband emission observed at early times gradually evolves into a narrow band with a peak wavelength at 1.18 μm. The time-resolved spectra are compared with the theoretical prediction of a model taking into account both the site distribution and the admixture of the 3T2 state into 1E state through spin-orbit interaction.