Sputtering of high-energy particles from the Ag{100} surface

The sputtering of atoms with high kinetic energies of hundreds of eV from the single-crystal surface due to energetic particle bombardment is studied using Ag $100% as a model system. Molecular-dynamics calculations show that these high-energy atoms tend to be preferentially sputtered along a major crystallographic direction, along which the atoms with sputtering energies of less than 50 eV are known to exhibit the minimum sputter intensity. The angular anisotropy exhibited in the azimuthal angle distribution of the high-energy atoms is mainly due to the anisotropic sputtering of the atoms from the second layer. Collision cascade analysis shows that the high-energy atoms may be ejected from the surface by a collision either directly from the primary particle or from a fast-moving surface particle after it travels energetically in a space between two adjacent $100% atomic planes perpendicular to the surface. At high ejection energies, there is also a significant increase in the relative contribution of the atoms sputtered from below the first atomic layer to the total sputter yield. The high-energy atoms ejecting from the lower layers tend to be focused to pass through the center of a triangular atomic feature on the surface, and then confined by a surface semichannel before leaving the surface. The use of the high-energy atoms for surface structural determination is discussed. The angular distribution of the low-energy atoms reflects more of the geometric structure of the first atomic layer, whereas the high-energy atoms exhibit more of the structural property of the second layer. @S0163-1829 ~98!05019-X#