Investigation of the local atomic arrangement on surfaces using low-energy ion scattering

Ions with energies around 1 keV are well suited for detecting atoms on solid surfaces and for investigating their relative arrangement. This is due to the large scattering cross-sections which are of the order of 10^–2Ų/sr. The conceptually simple method is limited by the fact that interaction potentials and, more so, charge exchange processes are only approximately known. Progress in low-energy ion scattering has recently been made by applying special scattering geometries and by using alkali ions, in addition to noble gas ions.Among the successful applications there are studies of the arrangement of atomic layers on supported catalysts, ordered adsorption systems on metal surfaces, surface reconstruction, and surface disordering due to defects and thermal motion. Energy spectra of recoil atoms and ions convey additional information. The fundamental physical features of low-energy ion scattering are discussed on the basis of examples of recent results.