A Method for Partially Incoherent Imaging of Crystalline Specimens in Conventional TEM

Published

October 16, 2008

Author(s)

Ian M. Anderson

Abstract

Quantitative imaging of crystalline specimens in conventional transmission electron microscopy (TEM) is inhibited by diffraction effects coherent scattering contrast that arises from the dynamical diffraction of the incident probe with atoms arranged on a crystal lattice. This coherent contrast can be damped out using a newly developed method in which TEM imaging is performed while operating the microscope in scanning transmission electron microscopy (STEM) mode. The method allows a TEM image to be acquired with an incoherent superposition of a range of incident beam orientations, bounded but comparable to the collection aperture semi-angle, . The method is equivalent through reciprocity to STEM annular dark field (ADF) imaging with an inner semi-angle of and an arbitrarily large outer angle. The lateral incoherence effected by high-angle scattering in Z-contrast imaging is provided by the raster of the illumination, thus allowing incoherent imaging with a minimum of atomic number contrast. Optimum settings and estimates of spatial resolution are provided for common microscope operating configurations, including aberration corrected TEM. The method is especially suitable for in-situ studies and quantitative imaging techniques, such as energy-filtered TEM compositional analysis and tomography, of the multiphase, polycrystalline specimens that are typically of interest in materials science.

Citation

Ultramicroscopy

Pub Type

Journals

Keywords

crystals, partial coherence, resolution, TEM imaging

Citation

Anderson, I. (2008), A Method for Partially Incoherent Imaging of Crystalline Specimens in Conventional TEM, Ultramicroscopy (Accessed April 19, 2024)