TIME-RESOLVED PHOTOLUMINESCENCE OF ALPHA-CENTERS IN NEUTRON-IRRADIATED SIO2

Photoluminescence in various types of silica (a-SiO2) both unirradiated and neutron irradiated has been studied in the range 10-300 K. The already reported alpha emissions at 4.25 eV and at 4.35 eV, whose respective excitation bands peak at 5.10 eV and 4.96 eV, have been found to be excited also in a band peaking at approximately 7.6 eV; the temperature dependence of their intensities has also been investigated for both, excitations. Time resolved emission spectroscopy excited by KrF excimer laser (5 eV) allowed the detection of the different lifetimes of the two a emissions. Similar studies on neutron irradiated quartz (c-SiO2) have evidenced the presence of the center emitting at 4.35 eV up to now observed only in a-SiO2.