Vacuum ultraviolet optical absorption band of non-bridging oxygen hole centers in SiO(2) glass

An intense broad vacuum ultraviolet (VUV) optical absorption band with peak at 6.8 eV and halfwidth approximate to 1.7 eV is identified in irradiated glassy SiO(2) and assigned to dangling oxygen bonds (non-bridging oxygen hole centers, NBOHC). It was selectively created by photolysis of silanol (SiO-H) groups by 7.9 eV photons of F(2) excimer laser at low temperature. Subsequent analysis by VUV absorption, time-resolved luminescence, and electron paramagnetic resonance spectroscopies during thermal annealing showed an exact correlation to the well-known 4.8 and 2 eV absorption and 1.9 eV luminescence bands of NBOHC. The estimated oscillator strength of the 6.8 eV band is f approximate to 0.05. This band may be one of the dominant causes of VUV optical absorption induced by excimer-laser irradiation of silica. (C) 2002 Elsevier Science Ltd. All rights reserved.