Experimental evidence for the Si-Si bond model of the 7.6-eV band in ${\mathrm{SiO}}_2$ glass

We have found a decrease in the intensity of the 7.6-eV band and the appearance of the Si-H band upon heating ${\mathrm{SiO}}_2$ glasses, which were prepared by a method involving processes of dehydration with ${\mathrm{Cl}}_2$ gas, in ${\mathrm{H}}_2$ gas. The absorption cross section of the 7.6-eV band evaluated from these changes is 7.5×${10}^{\mathrm{-}17}$ ${\mathrm{cm}}^2$, which is close to that of a band centered at 7.56 eV of the ${\mathrm{Si}}_2$${\mathrm{H}}_6$ molecule containing a Si-Si bond. These results give experimental evidence for the Si-Si bond model of the 7.6-eV band in unirradiated ${\mathrm{SiO}}_2$ glass.