The photoluminescence from hydrogen-related species in composites of SiO2 nanoparticles

Measurements of photoluminescence (PL) from composites of silica nanoparticles (the primary particle size 7 and 15 nm) as a function of heat treatment temperature show that the PL results from hydrogen-related species and thermally produced structural defects. The PL was induced by an ArF or Nd:YAG (yttrium-aluminum-garnet) laser (lambda(exc)=193 or 266 nm). The green PL exhibits a progression with spacings of about Delta nu=630 cm(-1) assigned to the bending vibration of equivalent to Si-H on the surface of particles. The spacings increase up to Delta nu=1200 cm(-1) when equivalent to Si-H and nonbridging oxygen (equivalent to Si-O .) form interfacial water species. (C) 1999 American Institute of Physics. [S0003-6951(99)00532-X].