Valence state and local atomic structure of copper in Cu-implanted silica glass

Copper implanted fused silica samples were investigated for the first time by depth-selective x-ray absorption techniques. X-ray absorption near-edge structure and extended x-ray absorption fine structure measurements were performed using both x-ray fluorescence yield and conversion electron yield detection configurations, with the aim to discriminate the contribution of the copper ions at different depths. The copper species were found in both oxidized and metallic states. A dependence of the oxidized copper amount on the depth was detected. Compositional analyses were made by means of secondary ion mass and Rutherford backscattering spectrometries. A matrix-damage related oxidation effect on copper atoms was confirmed.