Glass specimens were bombarded with 560MeV and 1.15GeV Ar ions at room temperature, and the resultant defects were investigated by using positron lifetime, electron paramagnetic resonance and ultra-violet absorption measurements. Free volumes which were about 0.065nm3 in size were revealed, in virgin specimens, by the corresponding ortho-positronium lifetimes. With increasing dose, the intensity of the component which corresponded to positronium decreased sharply. This was attributed to the preferred annihilation of positrons with electrons wandering in free volumes of the material. Optical absorption bands were introduced, by the bombardment, at about 5.8, 5 and 4.5eV. The absorption coefficients increased gradually with increasing dose. The electron paramagnetic resonance spectra of bombarded specimens revealed the presence of E' centers. The number density of the latter exhibited 2 distinct regimes according to the dose-dependence. In the low-dose range, the number density of E' centers obeyed an 0.23-power law dose-dependence. At high doses, it increased linearly with dose. The electron paramagnetic resonance spectra exhibited a fine structure which changed with dose.

Defects in SiO2 Glass Irradiated with High Energy Ar Ions. Z.Zhu, Y.Jin, C.Li, Y.Sun, C.Zhang, Q.Meng: Nuclear Instruments and Methods in Physics Research B, 1998, 146[1-4], 455-61