Conversion efficiency of graphite atomic-scale defects to etched pits in thermal oxidation reaction

Thermal oxidation of atomic defects on a graphite surface, produced by low energy (50-200 eV) impact of Ar⁺ and Kr⁺ ions, leads to the formation of pits with a diameter of several nm. These pits are generated from both carbon vacancy defects and interstitial defects, the latter formed by trapping of incident ions in-between graphite layers. The probability of the pit formation is measured for each type of defect. Nearly all vacancy defects (>90%) are developed into pits by thermal oxidation in air at 560°C, while only a small portion (<15%) of the interstitial defects are converted into pits.