Abstract
Spherical Aberration Free Focus (AFF) conditions for taking atomic resolution electron microscope images of single crystals and pseudo-Aberration Free Focus (ψ-AFF) conditions for taking atomic images of more than two adjoining single crystals are discussed by using diagrams of C s (spherical aberration coefficient) and Δf (defocus). Calculated image contrast in those conditions is shown for three individual crystals of MgO, MgAl 2O 4, Al 2O 3 and their adjoining crystal blocks. It is shown that at least two kinds of Bragg reflected waves can be in the AFF condition in each case, and thus the size of the aperture for limiting the waves becomes important in some cases, C s can be changed by changing the position of the specimen along the objective lens axis but highly coherent illuminating waves are needed for large C sand δf .
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
