Formation of paramagnetic defects in high-purity silica by high-energy ions

We investigated the paramagnetic defects formed by high-energy ions in amorphous SiO2 using electron spin resonance. We show that the variation of paramagnetic defect densities with both the residual range and the atomic number of the ion is not simply correlated with the total energy deposited in the sample, which is the major controlling parameter for other types of irradiation (γ rays, electrons). This specificity of ion irradiation is most likely related to the high local density of deposited energy. The observed populations of paramagnetic defects constitute a small fraction of the formed defects. However, their characteristics can be related to results on ion track structure obtained by small-angle scattering and track etching methods