Impact Collision Ion Scattering Spectroscopy

Abstract

Ion scattering spectroscopy (ISS) [1] is a real-space method that enables simultaneous analysis of the composition and structure of solid surfaces by utilizing elastic scattering of ions at the surfaces. In ISS, a low-energy ion beam impinges on the specimen surface at a given angle of incidence and the energy spectrum of the scattered ions is measured. If the ion and target atom masses (m, M) and the scattering angle H are given, the scattered-ion energy E (incident-ion energy, E 0) can be unambiguously determined by E ¼ E 0 m=ðm þ MÞ ½ Š 2 cos H þ ðM 2 =m 2 À sin 2 HÞ 1=2 h i 2 : ð1Þ Different target atoms accordingly yield different scattered-ion energies, thus enabling the composition analysis of the solid surfaces. If the angle of ion incidence or scattered-ion detection is scanned and the change in the energy spectrum is measured, the surface atomic arrangement can also be analyzed by utilizing two "classical" effects: the shadowing effect, which prevents scattering by an atom located behind another atom from the perspective of the incident ion; and the blocking effect, which prevents detection of an ion scattered by an atom nearer to the detector. By virtue of the use of low-energy ions (on the order of keV) in ISS,