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 impinging ions to substrate atoms to overcome the surface binding energy. Since ordinary physical sputtering models thus do not apply, the atomistic mechanisms underlying this "chemical sputteriug" effect are not well understood. We now describe how low-energy ions can cause erosion of atoms and molecules by colliding with and breaking chemical bonds between the atoms. In the particular case of hydrogen bombardment of amorphous carbon networks, we further show that this carl lead to erosion yields far exceeding those expected for a collisional process alone.