Intensities and Energy Spectra of Secondary Ions Sputtered from Fe-Al Alloys by Ar+ Ion Bombardment in Ultrahigh Vacuum

The main mechanism responsible for the emission of singly charged ions from ion-sputtered solid samples is known as the “surface excitation”, that is the electronic excitation of the outgoing particle during its separation from the target [1–3]. At a given velocity, such a process is governed by the electronic structure of the surface near the ejection point, and therefore is very sensitive to the local environment [4,5] . However the surface excitation model cannot explain the emission of multiply charged ions from light elements. In fact, to account for secondary ion emission from light metals, JOYES [6] early proposed a collisional mechanism where ionization results from Auger decay of collision-induced L-shell excitations and which is well supported by the observation of Auger electrons under ion bombardment [7].