Electron spin resonance studies on spots with brown rims on a vitreous silica surface formed by a silicon melt

Vitreous silica plates were immersed separately in a silicon melt at 1460 d egrees C for 4 h and 25 h. respectively in argon atmosphere. Electron spin resonance (ESR) and optical microscopy observations showed that the paramag netic species (g = 2.0049, peak to-peak line width (Delta H-pp) =7.0 G) exi sted at the center and the periphery of the spots with brown rims in the si lica plate subjected to 4 h immersion. It was revealed that both silicon ox ide (SiO1.49) and silicon monoxide (SiO1.04) have silicon dangling bonds (e .g., . Si = Si-3, . Si = Si2O, and . Si = SiO2) which have ESR parameters ( g = 2.0048, Delta H-pp = 7.5 G), The paramagnetic species in the spots with brown rims were estimated to be the silicon dangling bonds (e.g., . Si = S i-3, . Si = Si2O, and . Si = SiO2) in the silicon monoxides.