Near-threshold ion-induced defect production in graphite

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Abstract
Subplantation of the noble-gas ions He+, Ne+, Ar+, and Kr+ into graphite in the energy range of 10–150 eV with doses in the range of 1–15×1014 ions/cm2 has been studied by Auger electron spectroscopy (AES) and computer simulations. A technique based on AES line-shape analysis has been employed to describe quantitatively the ion-induced damage to the lattice. The carbon KLL AES line shapes and the AES spectra from subplanted Ne, Ar, and Kr were used to determine the ion penetration thresholds Ep, ion displacement thresholds Eth, and the lattice displacement energies Ed. The Ep’s scale linearly with the atomic radius of the projectiles. Defect production begins at Ep, although these energies are below Eth. A mechanism for defect production at energies below Eth based on noble-gas interstitials and lattice strain and distortion is developed. This process is modeled through the charmm molecular modeling program and the trim classical trajectory simulation.