Dependence of the Reactivity of Silicon Dioxide Layers on the Porous Structure

摘要

The effect of porosity on chemical reactivity can be considered in two respects: the first one is connected with the developed surface, so that the reaction proceeds not at the interface but over the volume; this phenomenon may be called macro-structural effect. The second effect is due to the change of the electronic structure of surface atoms, which causes the change of their chemical properties. This is micro-structural effect. A decrease in pore radius (down to less than 1 nm) causes distortions of the electronic structure of surface atoms, in particular due to strain, so any assessment of the reactivity of surface atoms is to rely on the consideration of changes in their electronic structure. It was demonstrated by modelling that the most probable mechanism of the passivation of the surface of alkyl-doped silicon dioxide layers under the action of VUV radiation is the impact on CH_3 groups. The proposed mechanism adequately explains the experimental FTIR spectra and the change of the reactivity of porous layers after VUV treatment.