Hyperthermal atomic oxygen beam irradiation effect on the Ti-containing DLC film

• Surface structure of Ti-DLC film was changed by the exposure to an atomic O beam.
• The C K NEXAFS and Ti L NEXAFS spectra of as-deposited Ti-DLC film changed drastically after exposure to atomic oxygen beam.
• The changes in the NEXAFS spectra are ascribable to desorption of C atoms as CO and/or CO2 from Ti-DLC film due to the irradiation of atomic oxygen beam.

Surface structural changes of Ti-doped diamond-like carbon (Ti-DLC) film exposed to a hyperthermal atomic oxygen beam were investigated using near-edge X-ray absorption fine structure (NEXAFS) spectroscopy using synchrotron radiation. The spectral shape of the C K NEXAFS spectrum of as-deposited Ti-DLC film resembled that of DLC film. After exposure to atomic oxygen, the spectrum resembled that of TiC powder. The sp2/(sp2 + sp3) ratio of as-deposited Ti-DLC film decreased drastically by exposure to a hyperthermal atomic oxygen beam. On the other hand, the spectral shape in the Ti L NEXAFS spectrum of as-deposited Ti-DLC film resembled that of TiC powder and became similar to that of TiO2 powder after exposure to atomic oxygen. These changes are ascribable to the desorption of C atoms as CO and/or CO2 from Ti-DLC film due to the irradiation of atomic oxygen beam. On the other hand, oxidized Ti was not desorbed from the Ti-DLC film. As a result, the sp2/(sp2 + sp3) ratio of C in the Ti-DLC film decreased, because residual C atoms were bonded to Ti atoms.