Sub-angstrom resolution of atomistic structures below 0.8 angstrom

Microcharacterization of defects is greatly facilitated with improvement in resolution. By improving temporal coherence (chromatic aberration) and com pensating spatial incoherence, we have achieved the goal of the 1 Angstrom microscope (O AngstromM) project at the US Department of Energy's National Center for Electron Microscopy by extending the limits of high-resolution t ransmission electron microscopy to sub-angstrom levels. The O AngstromM com bines focal-series image-processing software with a modified 300 keV electr on microscope equipped with a highly coherent field emission electron gun. By operating at an 'alpha -null' value of underfocus in order to minimize t he effects of spatial incoherence, and by reducing the O AngstromM's electr on-gun extraction voltage to improve temporal coherence, we are able to tra nsfer information below 0.8 Angstrom In a test specimen of silicon viewed i n the [112] orientation in the O AngstromM we are able to 'see' atoms separ ated by only 0.78 Angstrom. Sub-angstrom resolution at this level offers th e materials researcher an effective tool for the characterization of defect s with unprecedented precision.