Intense white luminescence of Sm2O3 irradiated with ultraviolet laser light under vacuum

When Sm2O3-powder compact and -microcrystal films are irradiated with 325 nm laser light at room temperature in an evacuated chamber, their photoluminescence (PL) intensities are enhanced enormously. Then, introducing oxygen gas into the specimen chamber, the intense PL state returns to the original weak one under the same laser light irradiation. Through many successive experiments, it is found that the spectral change is reversible under 325 nm laser light irradiation. After removing the 325 nm laser light irradiation, each PL-state is stored for a long time at room temperature under room light, in spite of any change of atmosphere. The PL excitation spectra indicate that the observed phenomenon may arise from photoinduced valence-number change of samarium ions and photoinduced oxygen defects