Energy distribution of secondary ions sputtered by Ar+ ion beam from indium surface

The energy distribution is investigated for atomic and cluster secondary ions sputtered by 18 keV Ar+ ions from the surface of polycrystalline indium under oxygen partial pressures ranging from 10-7 to 6.5 x 10-3 Pa. The measurements are performed using a secondary ion mass spectrometer. The energy dependence of the possibility of indium atom ionization is also determined. The energy distribution is measured for In+, In2+, In3+, In2O+, In3O+ ions. At low oxygen pressure only secondary ions Inm+ are observed in a mass spectrum. Spectra of In2O+ and In3O+ secondary ions are revealed at oxygen pressure of 1.3 x 10-3 Pa and above. It is concluded that the shape of In+ ion energy distribution is conditioned by specific features of charge taking on and conserving by an outgoing particle, these features associating with particle electronic configuration and band structure of the metal