Bismuth, by high-sensitivity low energy ion scattering

Abstract

Low energy ion scattering is an analytical technique with extreme surface sensitivity. It enables qualitative and quantitative elemental analysis of the outermost atomic layer. Straightforward quantification is possible by using well-defined reference samples, as the measured signal is related to known surface atomic concentration. Bi, like Pb, exhibits strong oscillatory behavior of backscattered ion yield when primary ion beam energy is varied. Here, we present the spectra of bismuth obtained by scattering of 4He+ ions in a wide range of energies (0.5–6.0 keV). These should cover a regularly used range of energies for He analysis and serve as standards or reference spectra for analysis of bismuth if the scattering angle is 145° or similar. For this purpose, high-purity foil cleaned by ion sputtering was used. The sensitivity of the instrument in use (high-sensitivity low energy ion scattering spectrometer) is defined by the 3 keV 4He+ spectrum of copper. The related atomic sensitivity and relative sensitivity factors are determined.