Thin MgO films with thicknesses ranging from 127 to 35 nm were prepared by pulsed laser deposition on Si substrates. The crystalline films were smooth (rms roughness 0.6â1.2 nm) with an average density of 3.5 g/cm3. Cathodoluminescence study revealed emissions peaked at 7.65 eV and ascribed to the edge emission of large radius exciton states as well as luminescence due to the F and F+ colour centres in the range of 2â4 eV. This luminescence is efficiently excited in the absorption band peaked at 6.2 eV and in the intrinsic absorption with the onset at 7.4 eV via energy transfer processes.