Diffusion of oxygen from substrate to the film was observed under the influence of large electronic excitation. CuO thin film similar to 210 nm on float glass was irradiated with 210 MeV I ions. We noticed the transport of oxygen from the substrate to the CuO him through the interface. The amount of oxygen transport From glass to the film was found to be fluence dependent. The loss of oxygen from the films was also observed. The erosion of Cu atoms was also observed beyond a fluence of 9.6 x 10(13) ions/cm(2). The measurements were performed by on-line elastic recoil detection using a large area position sensitive detector. Since the electronic energy loss dominates in the present case of 210 MeV I ions, the observed changes at the interface and surface are attributed to inelastic collisions of the incident ions with the atomic electrons in the sample. (C) 2000 Elsevier Science B.V. All rights reserved.