APPLICATION OF LOW-ENERGY NOBLE-GAS ION-SCATTERING TO THE QUANTITATIVE SURFACE COMPOSITIONAL ANALYSIS OF BINARY-ALLOYS AND METAL-OXIDES

Loci-energy noble-gas ion scattering (LEIS) probes the outermost atomi c layer of a material, bat a quantitative compositional analysis of th is layer is not straightforward. It is demonstrated that quantificatio n by calibration can be done, assuming that ion fractions and shieldin g effects are the same for the reference sample and sample of interest . These assumptions are critically evaluated and LEIS experiments on b inary alloys and metal oxides are presented that can partly verify the se assumptions. The LEIS measurements of a Cu-Au alloy and CuO powder as a function of initial energy indicate the absence of matrix effects in the ion fractions after scattering from the metal atoms in these s ystems. In metal oxides, shielding of surface metal atoms by shadowing /blocking and ion neutralization by neighbouring atoms can significant ly influence the quantification of the metal atom concentration and is determined by the local atomic arrangement as illustrated by LEIS exp eriments of CuO and ZnO samples. (C) 1998 John Wiley & Sons, Ltd.