Diffusion and outgassing of O2 in amorphous SiO2 silica nanoparticles with specific surface properties

Silica nanoparticles with hydrophilic and hydrophobic surface and average diameter of 12 and 40 nm are investigated to study the surface group influence on the diffusion process of molecular oxygen. The O₂ diffusion kinetics and molecular solubility are determined by Raman/Photoluminescence measurements. Thermal treatments up to 127°C in controlled atmosphere show that the surface chemistry of nanoparticles is not changed, the equilibrium emission of O₂ depends on nanoparticles surface properties, whereas the dynamics of diffusion is surface independent suggesting that surface groups could only affect overall content or detectability of interstitial molecules. The post loading outgassing in nanoparticles of 40 nm average diameters has evidenced a long term stability of embedded O₂ in a time scale of months a promising aspect for nanoprobing applications.