Photoacoustic spectroscopy of Co2+ in ZnGa2O4 and MgGa2O4

Abstract A photoacoustic study of cobalt-doped ZnGa 2 O 4 and MgGa 2 O 4 is presented. The observed visible bands are assigned to the spin-allowed electronic transition 4 A 2 ( 4 F)→ 4 T 1 ( 4 P). Comparison between the radiationless relaxation time, observed by the photoacoustic method, and the fluorescence decay time indicates that a radiation process is dominant for these samples.