Temporal and spatial resolution of scattered and recoiled atoms for surface elemental and structural analysis

Developments in low-energy ion scattering over the past 10 years have led t o new techniques for surface elemental and structural analyses. The fundame ntal physics involved in these new methods is summarized herein and some ex amples of the applications of the techniques are presented. Three major new developments are considered. First, time-of-flight scattering and recoilin g spectrometry (ToF-SARS) takes advantage of ToF techniques to detect simul taneously both ions and fast neutrals that are scattered and recoiled from surfaces, Elemental analyses are obtained by application of binary collisio n theory, and structural analyses are performed by rotation of the sample i n order to measure intensity changes as a function of incident and azimutha l angles. Second, scattering and recoiling imaging spectrometry (SARIS) tak es advantage of a large position-sensitive microchannel plate detector, cou pled with ToF techniques, to capture element-specific, time-resolved, spati al acid intensity distributions of scattered and recoiled atoms from surfac es. These images combine atomic scale microscopy and spatial averaging beca use they are created from a macroscopic surface area but they are directly related to the atomic arrangement of the surface at the subnanoscale level; the features of the images are sensitive to changes in interatomic spacing s at a level of < 0.1 Angstrom. Third, a classical ion trajectory simulatio n program, called scattering and recoiling imaging code (SARIC), which is d esigned specifically for structural interpretation of ToF-SARS and SARIS da ta, has been developed. This program allows quantitative comparison of expe rimental and simulated data for surface structure determinations. Copyright (C) 1999 John Wiley & Sons, Ltd.