High-Energy Ion Beam Analysis☆

High-energy ion beam analysis (IBA) techniques were developed in the second half of the twentieth century and are based on three types of ion–atom interactions: (a) electronic excitation in the case of particle-induced x-ray emission, (b) particle scattering from atomic nuclei in the case of elastic or Rutherford backscattering and elastic recoil detection analysis, and (c) nuclear reactions in the case of nuclear reaction analysis (NRA) or particle-induced γ-ray emission. These methods provide information about the nuclear mass number (A) or the atomic number (Z) of the atoms within a sample together with their concentration. Information about the chemical environment of the atoms is not routinely available with these methods, although the emerging method of secondary ion mass spectrometry using MeV ions (MeV-SIMS) is able to identify and quantify large organic and inorganic molecules on the surface of samples. Used in combination with advanced data processing methods to combine the data, these methods can provide a complete internally consistent elemental analysis of a sample. This is becoming known as Total IBA. The long penetration depth of MeV ions in solids naturally means that variations of concentration with depth become accessible and, with the particle backscattering methods, high-resolution concentration depth profiles may be obtained. This article outlines the ways in which MeV ions interact with atoms and solids and explains and illustrates how these interactions are used for analysis. The equipment required for this type of analysis is described.