Laser excited novel near-infrared photoluminescence bands in fast neutron-irradiated MgO·nAl2O3

• AFM and SPM were conducted to understand surface morphology of the unirrad and neutron-irradiated spinel.
• Novel photoluminescence band at 1685 nm along with weak bands at 1065 and 2365 was observed.
• Activation energy for luminescence quenching was estimated from Arrhenius equation.

New near-infrared photoluminescence bands were observed in neutron-irradiated spinel single crystal upon excitation by a 532 nm laser. The surface morphology of the unirradiated and fast neutron-irradiated samples was investigated using atomic force microscopy and scanning probe microscopy. Fast neutron-irradiated samples show a strong emission peak at 1685 nm along with weak bands at 1065 and 2365 nm. The temperature dependence of the photoluminescence intensity was also measured. At lower temperatures, the dominant peak at 1685 nm shifts toward lower energy whereas the other peaks remain fixed. Activation energies of luminescence quenching were estimated to be 5.7 and 54.6 meV for the lower and higher temperature regions respectively.