Electronic transitions in silica glass during heavy-ion implantation

Spectra of ion-induced photon emissions (IIPE) of silica glass were measured during implantation of 3 MeV Cu ions at a constant flux of 3–10 μA/cm 2 up to a fluence of 9×10 16 ions/cm 2. Three bands compose the IIPE spectra: a tail of the oxygen-deficient center band, the band of Cu + ions at 2.27 eV and the band of non-bridging oxygen hole center at 1.89 eV. Intrinsic defects of silica glass contribute to the IIPE at the onset of irradiation only. At fluences higher than 5×10 14 ions/cm 2, the fluence dependence of the Cu +-band of IIPE represents (a) the accumulation of Cu solutes preceding the nanoparticle formation and (b) no change of Cu solute concentration during nanoparticle growth. The intensity of the Cu +-band is proportional to the total concentration of Cu solutes. The balance of Cu solutes and Cu nanoparticles is sensitive to the ion flux. The concentration of Cu solutes necessary for nanoparticle formation cannot be attained at fluxes higher than 10 μA/cm 2.