Spatial resolution in transmission electron microscopy

We review the practical factors that determine the spatial resolution of transmission electron microscopy (TEM) and scanning-transmission electron microscopy (STEM), then enumerate the advantages of representing resolution in terms of a point-spread function. PSFs are given for the major resolution-limiting factors: aperture diffraction, spherical and chromatic aberration, beam divergence, beam broadening, Coulomb delocalization, radiolysis damage and secondary-electron generation from adatoms or atoms in a matrix. We note various definitions of beam broadening, complications of describing this effect in very thin specimens, and ways of optimizing the resolution in bright-field STEM of thick samples. Beam spreading in amorphous and crystalline materials is compared by means of simulations. For beam-sensitive specimens, we emphasize the importance of dose-limited resolution (DLR) and briefly recognize efforts to overcome the fundamental resolution limits set by the wave and particle properties of electrons.

Automated summary

This article reviews the practical factors that determine the spatial resolution of TEM and STEM, and discusses the advantages of representing resolution in terms of a point-spread function. The article provides the point-spread functions for various resolution-limiting factors and compares beam broadening in different materials. Additionally, the importance of dose-limited resolution (DLR) for beam-sensitive specimens is emphasized, along with efforts to overcome the fundamental resolution limits.