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This chapter contains an overview of studies on elastic and inelastic scattering of ions from single crystal surfaces. Not only studies that provide surface structure data are included, but also studies in which the basics of the ion-surface interaction are investigated. This chapter briefly discusses principles of ion scattering spectrometry with emphasis, of course, on surface structure determination. The principle of the ion scattering spectrometry technique is based on the negligible small wavelength of probing particles. Ion scattering from crystals is essentially a classical phenomenon. Among the many techniques applied in surface science, low energy ion scattering spectrometry (LEIS) has its merits mainly in the field of surface composition and surface structure analysis. Initially, the subject of most LEIS studies was either surface composition - often different from the bulk because of segregation or adsorption - or ion scattering phenomena. Large scattering cross sections imply on the one hand that ions do not penetrate deep into a solid, making LEIS a surface sensitive technique. On the other hand, they imply that detected ions have often collided with more than one atom. Consequently, ions reflected into the same direction may have followed very different trajectories inside a crystal or just above an outermost atomic layer. Not surprisingly, Monte Carlo computer simulations are used extensively to study these complex multiple scattering mechanisms. |
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