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 (${\lambda }_{\mathrm{exc}}\text{=193}$ or 266 nm). The green PL exhibits a progression with spacings of about $\text{Δν=630\hspace{0.05em}}{\mathrm{cm}}^{\mathrm{-1}}$ assigned to the bending vibration of ≡Si–H on the surface of particles. The spacings increase up to $\text{Δν=1200\hspace{0.05em}}{\mathrm{cm}}^{\mathrm{-1}}$ when ≡Si–H and nonbridging oxygen (≡Si–O•) form interfacial water species.