High resolution time-of-flight low energy ion scattering

Low energy ion scattering (LEIS) is a well known technique for quantitative composition and structure analysis. Two different detection methods can be used in a LEIS experiment, i.e. an electrostatic analyzer or a time-of-flight (TOF) spectrometer. Both techniques have specific advantages. Nevertheless, the time-of-flight technique surpasses usual electrostatic analyzers used in LEIS in terms of energy resolution. The possibility to measure ions and neutrals, and the better energy resolution permit to study neutralization or charge exchange processes in much more detail.

Here we present a TOF–LEIS setup with an energy resolution of better than 0.4% for 3 keV He ions and report experimental results for 3 keV He ions backscattered from a polycrystalline Cu target. The resulting ion spectrum shows interesting inherent features, which are analyzed. Possible causes for the appearance of these features are discussed.