A combined time-of-flight and electrostatic analyzer for low-energy ion scattering

A new instrument for low-energy ion scattering (LEIS) is presented which employs a combination of electrostatic and time-of-flight analysis. In this instrument, electrostatic analysis is used to determine the kinetic energy of the ions, and flight-time analysis is used to select the mass of the ions. The combination allows us to discriminate the signals resulting from particles with a different mass than the primary ions, resulting in a very efficient suppression of signals caused by sputtered particles. The suppression of signals from sputtered particles enables more accurate determination of LEIS signals, especially for light elements. This technique is especially suited for the study of polymers and oxides, but can also be valuable for determination of low concentration of heavier elements. In this article the design of the instrument is presented and the method is demonstrated by some examples of LEIS spectra.