The 1s-State Analysis Applied to High-Angle, Annular Dark-Field Image Interpretation—When Can We Use It?

Abstract

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 1sstate is sufficiently localized to contribute a signal to the high-angle detector. This article shows that non-1sstates do make a significant contribution for certain incident probe profiles. The contribution of the 1sstate to the thermal diffuse scattering is calculated directly. Sub-Ångstrom probes formed by Cs-corrected lenses excite predominantly the 1sstate and contributions from other states are not very large. For probes of lower resolution when non-1sstates are important, the integrated electron intensity at the column provides a better estimate of image intensity.