Sputtering and reflection under cluster bombardment of solids

Using molecular-dynamics simulation, we study the sputtering induced by energetic impacts of projectile clusters containing N=100 and 1000 atoms. Both a metallic target and a van-der-Waals-bonded material are studied. We focus on self-bombardment at perpendicular incidence. The total emission yield is composed of the sputter yield of the target material and the reflection yield of reflected projectile cluster atoms. The dependence of these yields on the impact energy shows a slow transition from reflection- to sputter-dominated emission. Similarities and differences between the emission yield of metals and of van-der-Waals-bonded materials are discussed.