Unveiling the interaction regimes between atomic oxygen and amorphous carbon surface depending on incident energy

Abstract

The chemical reactions between atomic oxygen (AO) and solid surface are particularly crucial for numerous fundamental fields. However, it is lack of clearly understanding the reaction mechanisms between AO and the solid surface because the complex interaction dynamics are extremely difficult to be measured experimentally and to be modelled theoretically. In this work, the reactive molecular dynamics simulations are conducted to fully reveal the interactive mechanisms of AO irradiation on the amorphous carbon surface. As the incident energy (E) increases, our simulations demonstrate three distinct interaction regimes: (I) surface oxidation without carbon removal, (II) surface oxidation accompanied by minor material removals, and (III) continuous material removal. The first critical energy (E1) of ∼3.5 eV as the boundary between regime I and II is related to the dissociative energy of C–C bonds. The second critical energy (E2) of ∼6.5 eV as the boundary between regime II and III corresponds to the largest repulsion energy that the oxidized surface could provide. We further establish a phenomenological model to quantitatively describe how the rebound ratio varies with incident energy and surfacial oxygen density, which not only fit all simulation data perfectly but also give a very precise prediction of E2 value.