Measurements of the photoluminescence from composites of 7 and 15nm silica nano-particles, as a function of the heat-treatment temperature, showed that the photoluminescence resulted from H-related species and thermally generated structural defects. The photoluminescence was stimulated by using a 193 or 266nm laser. The green photoluminescence exhibited a progression, with spacings of about 630/cm being attributed to bending vibrations of =Si-H on the particle surfaces. The spacings increased up to 1200/cm when =Si-H and non-bridging O (=Si-H•) formed interfacial water species.

The Photoluminescence from Hydrogen-Related Species in Composites of SiO2 Nanoparticles. Y.D.Glinka, S.H.Lin, Y.T.Chen: Applied Physics Letters, 1999, 75[6], 778-80