Time dependence of silica optical properties during the implantation of fast hydrogen ions: Experiment

The luminescence technique has been applied to study long-time hydrogen ion implantation of silica. It was found that the changes of the spectrum shape for the luminescence radiation are caused by diffusion of hydrogen from the implanted layer. Analysis of the luminescence radiation spectra showed that hydrogen passivated the non-bridging oxygen hole centers (HBOHCs) and modified the oxygen deficiency centers (ODC). As the absorption dose grows a different behavior of luminescence in the blue (maximum at 456 nm) and the red (maximum at 645 nm) bands is demonstrated. Luminescence radiation intensity associated with the ODCs increased during the implantation due to the growth of modificated ODC’s contribution. At the same time luminescence radiation intensity associated with NBOHCs had a non-monotonic dependence on the absorption dose. On the basis of our theoretical model and the experimental data, we calculated the average radiation-enhanced diffusion coefficient of hydrogen, the product of average value of the cross-section of the radiation defect creation and the initial portion of defects and the reaction rate constant for non-bridging oxygen passivation by the hydrogen.