Defect-related visible luminescence of silica nanoparticles

We have investigated the visible emission of silica nanoparticles by time-resolved luminescence spectra. We have characterized the spectroscopic properties of the blue band, centered around 2.8 eV, peculiar of as received samples and we have evidenced the effects induced by high power UV laser irradiation on the emitting defects. Moreover, the comparison with the luminescence of samples thermochemically treated in controlled atmosphere allows us to critically discuss the structural model proposed in the current literature