Study of atomic excitations in sputtering with targets partially covered with oxygen

Abstract

We bombarded pure elemental targets of beryllium, boron, magnesium, aluminium, silicon, titanium and gold with 80 keV Ar + ions and studied the excitation of sputtered atoms or ions under ultrahigh vacuum conditions as well as with oxygen present at the target surface. The measurements on magnesium, aluminium, silicon and titanium were made at projectile incidence angles from 0° to 85°. Excitation probabilities for gold were found to be very little influenced by oxygen, but for beryllium, boron, magnesium, aluminium, silicon and titanium the excitation probabilities were in many, but not all, cases found to depend strongly on the oxygen pressure as well as on the beam current density. This indicates that the excitation mechanism is markedly dependent on the initial electronic conditions in the solid.