Automated electron tomography with scanning transmission electron microscopy
Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA.Journal of Microscopy (Impact Factor: 2.33). 01/2008; 228(Pt 3):406-12. DOI: 10.1111/j.1365-2818.2007.01859.x
We report the successful implementation of a fully automated tomographic data collection system in scanning transmission electron microscopy (STEM) mode. Autotracking is carried out by combining mechanical and electronic corrections for specimen movement. Autofocusing is based on contrast difference of a focus series of a small sample area. The focus gradient that exists in normal images due to specimen tilt is effectively removed by using dynamic focusing. An advantage of STEM tomography with dynamic focusing over TEM tomography is its ability to reconstruct large objects with a potentially higher resolution.
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ABSTRACT: The structural and morphological characteristics of nanomaterials determine both the prospects for their use and their risks to the environment and to human life. An approach to controlling nanocrystalline materials that takes into account the variations of the structural and morphological characteristics in the nanoregion has been considered. Transmission electron microscopy (TEM) meets the requirements of this approach most fully. TEM cannot become a control instrument without adequately changing the way it is used and reconstructing the hardware used, and the manufacturers, microscopists, and structural information users must realize their necessity and features. In this paper an attempt is made at collecting information concerning the above-mentioned groups. The scope of control-relating problems is outlined, and a concept based on the two-stage implementation is considered, where the size and structural fractions of the nanomaterials are determined at stage one and the characteristics of these fractions are determined at stage two. This approach is based on the fully automated measurements at stage one.
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