A spectroscopic examination of carbon fiber cross sections using XPS and ISS Original Research Article

Multiple transverse sections of type II, PAN-based carbon fibers (unsized and commercially treated) were investigated using X-ray photoelectron spectroscopy (XPS) and ion scattering spectroscopy (ISS). No previous XPS/ISS spectra of carbon fiber cross sections have been reported. The data are compared to angle-resolved XPS (ARXPS)/ISS spectra acquired from external (longitudinal) fiber surfaces in order to assess the experimental technique and aid spectral interpretation. The spectra are consistent with nitrogen and oxygen concentration profiles that decrease overall from the fiber surface inward to the fiber core. Oxygen is present primarily as COH within the fiber cores, with increasing amounts of CO and COOH groups near the fiber skin. The spectra also reveal the presence of zinc, sodium and calcium within the fiber cores.