Fine structure of the images of atoms in 011‐gold crystals in various Bragg reflecting conditions

Abstract

SUMMARYFine structures with petal and horseshoe shape contrast have been observed in the high resolution electron microscope images of atoms in a 011 gold crystal in deviated Bragg reflecting conditions. The images with such fine structures have been recorded by using only the beams of 000, four 111 and two 200 reflections with axial illumination. The contrast of the images has been discussed by the many beam dynamical theory of electron diffraction and the image formation theory considering the spatial and temporal coherence of the electron waves. It has been noted that the temporal coherence has much more effect on the change of image contrast than the spatial coherence. The imaging conditions have been analysed in terms of Fourier images and the aberration free focus conditions.