Photoluminescence band near 2.2 eV in γ-irradiated oxygen-deficient silica glass

Our previous studies have reported different radial distributions of the 2.25 eV photoluminescence (PL) band (full width at half maximum (FWHM): ∼0.4 eV, decay time (τ): ∼25 ns) under 3.8 and 4.66 eV excitation in γ-irradiated oxygen-deficient silica glass. As a result of our measurements, we believe that the origin of this PL band is different for 3.8 and 4.66 eV excitations. In order to understand this difference better, we measured the time-resolved PL spectra and decay time of the near 2.2 eV band under 3.49 and 4.66 eV excitation in γ-irradiated oxygen-deficient silica glass. We have found two PL bands at approximately 2.2 eV in the γ-irradiated oxygen-deficient silica glass. One band was observed at 2.25 eV (described above) under 4.66 eV excitation; and the other, at 2.15 eV (FWHM: ∼0.5 eV, τ: ∼150 ns) under 3.49 eV excitation. Two PL bands, one at 2.15 eV and the other at 2.25 eV coexist with excitation at 3.49, 3.8 and 4.66 eV. From our results, we conclude that the difference in the radial distributions of the 2.25 eV PL under 3.8 and 4.66 eV excitation is due to the 2.15 eV PL band. The main component of the observed PL intensity under 3.8 eV excitation was the 2.15 eV PL component, and the main component of the observed PL intensity under 4.66 eV excitation was the 2.25 eV PL component.