Structural Modification Processes in Bulk and Nano-sized Amorphous SiO2 Systems.

Near-Infrared emission of O2 embedded in amorphous SiO2 nanoparticles

We report an experimental study on the emission properties of O2 molecules loaded by a thermal diffusion process at 200 °C into high-purity silica nanoparticles with mean diameters of 7 and 40 nm. The embedded O2 features a singlet to triplet emission band peaked at 1272 nm in agreement with the band observed for bulk silica materials. The photoluminescence excitation spectra have been determined in the visible and in the infrared range and are characterized by narrow bands peaked at 691, 764,and 1069 nm, respectively. By comparison of the transition energies, the vibrational quanta have been determined for the ground and for both the excited states; the values found are lower than the corr…