Observation of room temperature photoluminescence in proton irradiated SrTiO3 single crystal

We have irradiated SrTiO3 single crystal with 3 MeV-proton (H+) beam and found that blue image-, green image- and infrared image- frequency photoluminescence (PL) are induced simultaneously at room temperature. TEM and EELS analyses show that an oxygen-deficient amorphous layer is formed at the crystal surface by the proton irradiation. Possible origin of the PL-effect is discussed.