Spectroscopic study of plasma-facing graphite tiles modified by electron and proton irradiation

We have carried out Raman, electron spin resonance (ESR), and X-ray photoemission (XPS) spectroscopy measurements on the graphite tiles modified by electron and proton irradiation. While increase in local order was observed in the electron-irradiated sample, structural disorder and amorphization were revealed in the proton-irradiated sample, with much reduced electrical conductivity. Besides, a narrow ESR peak attributed to localized spins, closely associated with C-OH bonds as identified by the XPS measurements, was detected in the proton-irradiated sample. (C) 2011 Elsevier B.V. All rights reserved.