LEIS  

Low Energy Ion Scattering (LEIS) yields quantitative information on the atomic composition of the outermost atomic layer of a solid, making LEIS the most surface sensitive analytical method. In LEIS, low energy noble gas ions with a kinetic energy of a few keV are aimed at the surface. The energy of each backscattered ion is characteristic for the mass of the corresponding collision partner, i.e. a surface atom. This enables LEIS to do element analysis of the surface. The use of modern double toroidal analysers developed in the group of Prof. Hidde Brongersma at the University of Eindhoven has lowered the detection limits into the ppm range for heavy elements and into the percent range for light elements. Ions that are scattered from depths up to 10 nm can also be detected and lead to a signal that is characteristic for the particular layer composition and thickness. That makes it possible to analyse the chemical build-up of the solid near the surface without sputtering (static depth profiling).

LEIS analysis is performed in ultra high vacuum. This means that samples need to be sufficiently vacuum compatible. With respect to sample topography there are no special requirements. Both atomically smooth single crystals and extremely rough catalyst powders can be analysed. Because of the high surface sensitivity of the method sometimes hydrocarbons that are adsorbed from the ambient air need to be removed prior to analysis. The necessary equipment is integrated in modern LEIS instruments.

A description of the LEIS principle and typical applications for the analytical technique can be found here:

Synonyms / Related Techniques

  • High-Sensitivity Low Energy Ion Scattering (LEIS)
  • Ion Scattering Spectroscopy (ISS)

Case Studies