C 1s Binding-Energy Shift of Pyrolytic Graphite Bombarded by keV-Deuterium Ions

抄録

As a basic study of plasma-wall interactions, chemical state of graphite basal face after deuterium bombardment are studied by means of X-ray photoelectron spectroscopy. As the fluence of deuterium ions with energy of 1 or 4 keV is increased from 10¹⁴ to 10¹⁸ ions/cm², the C is line is observed to shift towards the lower binding energy at first, down to the minimum by about 0.2 eV and then towards the higher energy up to an asymptotic value of about 0.2 eV higher than the initial position. The first negative shift is due to lattice dis-placement at the target surface, and the subsequent positive shift is due to the deuterium trapping at the graphite surface. The fluence dependence of the observed C is shift is ex-plained by a simple saturation model.