FROM SCATTERING AND RECOILING SPECTROMETRY TO SCATTERING AND RECOILING IMAGING

Anew ion scattering technique, called scattering and recoiling imaging spectrometry (SARIS), is being developed. The SARIS technique uses a large, position sensitive microchannel plate (MCP) and time-of-flight methods to capture images of scattered and recoiled particles from a p ulsed keV ion beam. These images combine the advantage of atomic scale microscopy and spatial averaging simultaneously since they are create d from a macroscopic surface area but they are directly related to the atomic arrangement of the surface. This paper describes the basis of the SARIS technique, the instrument which is under development, and th e scattering and recoiling imaging code (SARIC) for simulation of the classical ion trajectories. Time-of-flight scattering and recoiling sp ectrometry (TOF-SARS) data are used to emulate the SARIS images for th e case of 4 keV Ne+ scattering from a Pt{111} surface. The observed sc attering intensity patterns ate characterized by their complex and ric h structure. These experimental images are simulated by use of the SAR IC program. The abundance of information contained in the images can b e used to identify the type of surface being studied and its structure . The extraction of numerical values for the interatomic spacings, rel axations, reconstructions, and adsorbate site positions is accomplishe d by comparing the experimental and simulated images. Quantitative com parisons are made through the use of a reliability, or R, factor, whic h is based on the differences between the two images. The SARIS develo pment will move low energy ion scattering into the realm of surface im aging techniques.