Vacuum ultraviolet excitation of the 2.7 eV emission band in neutron irradiated silica

The temperature dependence of the photoluminescence induced at 2.7 eV by ultraviolet (UV) and vacuum ultraviolet (VUV) excitation of neutron irradiated (1021 n/m2 and 1022 n/m2) KU1 and KS-4V high purity silica, with different OH content, have been studied. Commercial silica Infrasil 301 has also been studied for comparison. At the highest neutron fluence and at the same temperature, the three irradiated silica grades show similar excitation spectra. Two close UV excitation bands, which show opposite temperature dependence, are observed at 4.8 and 5.1 eV. The 4.8 eV band, related to the triplet–singlet transition in SiODCs(II), decreases on decreasing temperature from 300 to 10 K and the band at 5.1 eV, probably related to SiODCs(I), is observed only at very low temperatures (∼10 K). An important VUV excitation structure, observed at low temperature, could also be related to SiODCs(I). A shift of the irradiated bands is detected at low temperature.