The 1s-state analysis applied to high-angle, annular dark-field image interpretation--when can we use it?
A small probe centered on an atomic column excites the bound and unbound states of the two-dimensional projected potential of the column. It has been argued that, even when several states are excited, only the 1s state is sufficiently localized to contribute a signal to the high-angle detector. This article shows that non-1s states do make a significant contribution for certain incident probe profiles. The contribution of the 1s state to the thermal diffuse scattering is calculated directly. Sub-Angstrom probes formed by Cs-corrected lenses excite predominantly the 1s state and contributions from other states are not very large. For probes of lower resolution when non-1s states are important, the integrated electron intensity at the column provides a better estimate of image intensity.
Department of Applied Physics, University of Technology, Sydney, P.O. Box 123, Broadway, NSW 2007, Australia. Geoff.Anstis@uts.edu.au
Geoffrey R
GR
Anstis
D007091:Image Processing, Computer-Assisted; D017348:Microscopy, Electron, Scanning Transmission / Q000295:instrumentation / Q000379:methods*; D008962:Models, Theoretical; D009010:Monte Carlo Method; D012542:Scattering, Radiation