INHOMOGENEOUS BROADENING OF OPTICAL-TRANSITIONS DOMINATED BY LOW-SYMMETRY CRYSTAL-FIELD COMPONENTS IN CR3+-DOPED GALLOGERMANATES

The optical spectroscopy of strong- and weak-field sites of Cr3+-doped gallogermanates have been investigated using fluorescence line narrowing, selective excitation, and selective fluorescence lifetime measurements. A statistical model has been used to model the spectroscopic data obtained from the fi-line fluorescence of the strong-field sites whilst an adiabatic model of the spin-orbit and electron-phonon coupling interactions has been used to model the broadband absorption and emission of the weak-field sites. For both strong- and weak-field sites it is shown that inhomogeneous broadening is dominated by the nonoctahedral component of the crystal field rather than by variation of the octahedral crystal-field strength.