Physical disorder and optical properties in the vacuum ultraviolet region of amorphous SiO(2).

The optical absorption of point-defect-free SiO(2) glass in the vacuum ultraviolet region is primarily controlled by the concentrations of three- and four-membered ring structures composed of heavily strained Si-O-Si bonds. The main channel of color center formation by F(2) excimer laser (7.9 eV) irradiation is not Frenkel-defect generation of oxygen via two-photon absorption processes but a pair generation of E' and nonbridging oxygen hole centers by the one-photon excitation of these strained bonds with 7.9 eV photons.