Electron Spin Resonance Studies on Spots with Brown Rims on a Vitreous Silica Surface formed by a Silicon Melt

Abstract

Vitreous silica plates were immersed separately in a silicon melt at 1460°C for 4 h and 25 h, respectively in argon atmosphere. Electron spin resonance (ESR) and optical microscopy observations showed that the paramagnetic species (g=2.0049, peak-to-peak line width (ΔH _pp) =7.0 G) existed at the center and the periphery of the spots with brown rims in the silica plate subjected to 4 h immersion. It was revealed that both silicon oxide (SiO_1.49) and silicon monoxide (SiO_1.04) have silicon dangling bonds (e.g., •Si≡Si₃, •Si≡Si₂O, and •Si≡SiO₂) which have ESR parameters (g=2.0048, ΔH _pp=7.5 G). The paramagnetic species in the spots with brown rims were estimated to be the silicon dangling bonds (e.g., •Si≡Si₃, •Si≡Si₂O, and •Si≡SiO₂) in the silicon monoxides.