Surface chemical composition of fluorocarbon films deposited onto indium-tin-oxide (ITO) substrates was modified by 2.0 keV Ar-divided by irradiation with doses of up to 2.6 x 10(13) ions/cm(2). The effect of ion irradiation on the chemical composition and bonding configuration of the upper-surface and sub-surface regions were monitored by high-resolution angle-resolved X-ray photoelectron spectroscopy (AR-XPS). It was found that the as-deposited films compose of a distribution of CF, CF2, CF3 and C-C chemical states. C Is line-shape analysis of XPS spectra measured at grazing and normal emission angles shows that as a result of the irradiation, the population of the CF3 and CF2 chemical states were preferentially depleted from the film's surface resulting in an increased population of the CF and C-C chemical states in the upper-surface region of the film. It is suggested that low energy ion irradiation can be used to chemically modify the surface of fluorocarbon films. (C) 2003 Published by Elsevier B.V.