Element-, time- and spatially-resolved images of scattered and recoiled atoms

Abstract

Element-specific, time- and spatially-resolved images of keV scattered and recoiled atomic ions plus fast atoms are exploited as a new technique of scattering and recoiling imaging spectrometry (SARIS). SARIS, an outgrowth of time-of-flight scattering and recoiling spectrometry (TOF-SARS), uses a large position-sensitive microchannel plate and TOF methods to capture images of energetic atoms which are scattered and recoiled from surfaces using a pulsed keV ion beam. The atoms are dispersed according to their velocities as a function of projectile/target atom masses and deflection angles. The spatial distributions of these atoms are captured by the MCP in time-resolved frames as short as 10 ns. Classical ion trajectory simulations provide a good description of the interactions, allowing direct simulation and interpretation of the experimental images. The images combine atomic scale microscopy and spatial averaging since they are created from a macroscopic surface area but they are directly related to the atomic arrangement of the surface at the sub-nanoscale level; the accuracy for measurement of interatomic spacings is expected to be better than 0.01 Å. Example data is presented for Pt{111}and Au{110}.