X-ray and neutron reflectometry study of copper surface reconstruction   caused by implantation of high-energy oxygen ions
  Combination of neutron and X-ray reflectometry was used to study the vertical structure of 100 nm-thin copper films with implanted oxygen ions of energy E = [10-30] keV and doses D=[0.2-5.4]x$10^{16}$ $cm^{-2}$. The study shows that oxygen ion implantation with an energy of E = 30 keV leads to the formation of a 3 nm thick layer on the surface. Density and copper/oxygen stoichiometry of the observed surface layer are close to $Cu_2O$ oxide. We attribute the $Cu_2O$ oxide formation to highly mobilized copper atoms generated by stimulated ion implantation. 
Yu. N. Khaydukov, O. Soltwedel, Yu. A. Marchenko, D. Yu. Khaidukova,   A. Csik, T. Acart\"urk, U. Starke, T. Keller, A. G. G...
cond-mat.mtrl-sci