Time scales of chemical sputtering of carbon

Chemical sputtering of carbon by D and D2 impact is studied at impact energies ranging from 7.5 to 30 eV/D using molecular dynamics simulations that mimic experiment, as closely as possible. This entails a careful analysis of the time scales involved in the deuterization of carbon by particle bombardment. The substrate structure is heavily modified by cumulative impacts, and the sputtering yields change with bombardment time, eventually reaching a quasi-steady-state. Such state is reached at approximately the same fluence of D and D2 impact. The yields of the hydrocarbons in this quasi-steady-state regime are in good agreement with experiment, and are significantly larger and of different structure than those from the unmodified surfaces.