Abstract
The initial studies using the Nion third-order aberration corrector in the scanning transmission electron (STEM) were intended to characterize the probe size performance and to explore some limits of the performance. It was found that multislice calculations are needed to fully understand the imaging results at this probe size, and that it is possible to use measured aberration coefficients to accurately define the initial probe wave function for the multislice simulation. An efficient multislice method was developed to deal with high-angle annular dark-field (HAADF) STEM imaging in thin nonperiodic structures. New instrumental capability often raises new questions. These preliminary studies are very good examples of this behavior. In the past, single-atom behavior was not normally visible, particularly within crystalline structure, and so the possibility of atomic movement during imaging was not considered in the absence of obvious extensive damage.