  An optical absorption (OA) band of interstitial dichlorine monoxide molecules
with peak at 4.7 eV and halfwidth 0.94 eV is identified in F2 laser -
irradiated (photon energy=7.9 eV) synthetic silica glass bearing both
interstitial O2 and Cl2 molecules. Alongside with intrinsic defects, this OA
band can contribute to solarization of silica glasses produced from SiCl4.
While the formation of ClClO is confirmed by its Raman signature, its
structural isomer ClOCl may also contribute to this induced OA band. Thermal
destruction of this band between 300C and 400C almost completely restores the
pre-irradiation concentration of interstitial Cl2. An additional weak OA band
at 3.5 eV is tentatively assigned to ClO2 molecules. The strongly forbidden
1272nm infrared luminescence band of excited singlet O2 molecules was observed
at 3 eV-3.5 eV excitation, demonstrating an energy transfer process from
photoexcited triplet Cl2 to O2. The energy transfer most likely occurs between
Cl2 and O2 interstitial molecules located in neighboring nanosized interstitial
voids in the structure of SiO2 glass network.
