Chemical sputtering of ATJ graphite induced by low-energy bombardment

Results of chemical sputtering of ATJ graphite by impact of D 2 + in the energy range 10–250 eV/D are presented. Our experimental approach is based on the use of a quadrupole mass spectrometer (QMS) which samples the partial pressures of selected mass species in the scattering chamber resulting from the incident ion beam. Based on in situ measurements of cracking patterns and QMS sensitivities using calibrated leaks, sputtering yields are presented for the production of methane and acetylene for sample temperatures of 300 K and 800 K. In the energy range 10–60 eV/D, CD ₄ appears to be the dominant light stable hydrocarbon detected at room temperature. With increasing D 2 + energy, its contribution is found to decrease, while the contribution of C ₂D ₂ is virtually unchanged. In contrast to what is observed for the sample at room temperature, at 800 K a dramatic increase in the CD ₄ production is observed with increasing beam energy, which is also manifested in the production of C ₂D ₂, although to a smaller degree.