Ion-Beam Analysis of Polymer Surfaces and Interfaces

Abstract

Ion-beam analysis of chemical composition as a function of depth is by now well-established for inorganic materials and is an important method of investigating growth of thin films. It has been applied to polymers much more recently, perhaps because fairly obvious problems with radiation damage discouraged workers in this field initially. Ion-beam analysis has developed, however, into a analytical tool that complements other methods, such as x-ray photoelectron spectroscopy and neutron reflection, very well. The purpose of this short article is to give the reader an introduction to its current uses in polymers.The ion beams of ion-beam analysis are typically highly energetic (1–5 MeV) beams of 4He++. While other beams are used, for example, 3He and 15N, alpha particle beams are used in the vast majority of experiments reported in the literature. Two major categories of experiments are carried out with such beams. Rutherford backscattering (RBS) spectrometry to detect heavy elements in the polymer and forward recoil spectrometry (FRES) (also known as elastic recoil detection) to detect the isotopes hydrogen and deuterium. The basic principles for each method are similar.