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 em ploys a combination of electrostatic and time-of-flight analysis. In this i nstrument, electrostatic analysis is used to determine the kinetic energy o f 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 part icles with a different mass than the primary ions, resulting in a very effi cient 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 d etermination of low concentration of heavier elements. In this article the design of the instrument is presented and the method is demonstrated by som e examples of LEIS spectra. (C) 1999 American Institute of Physics. [S0034- 6748(99)01010-2].