Threshold energy for photogeneration of self-trapped excitons in SiO2

Abstract
The excitation spectrum of the 2.8-eV luminescence band of crystalline SiO2 has been measured in a photon energy range between 6 and 14 eV at 77 K. We find that the onset of the 2.8-eV luminescence occurs at 8.3 eV, which is nearly equal to the fundamental optical absorption edge of SiO2. This result supports strongly the model that the band is due to the radiative recombination of the self-trapped excitons.