Bond-breaking mechanism of sputtering

Energetic ions are known to be able to erode atoms from a solid even when a collisional mechanism cannot transfer enough kinetic energy from the impin ging ions to substrate atoms to overcome the surface binding energy. Since ordinary physical sputtering models thus do not apply, the atomistic mechan isms underlying this "chemical sputteriug" effect are not well understood. We now describe how low-energy ions can cause erosion of atoms and molecule s by colliding with and breaking chemical bonds between the atoms. In the p articular case of hydrogen bombardment of amorphous carbon networks, we fur ther show that this carl lead to erosion yields far exceeding those expecte d for a collisional process alone.