Developing image-contrast theory and analysis methods in high-resolution electron microscopy

It is reviewed that the structural information obtained from high-resolution electron microscope images can be greatly improved by utilizing a group of analysis methods developed based on an image-contrast theory derived particularly to show the image-intensity change with the sample thickness. It is introduced that the experimental images that do not represent the structures of examined samples can be transformed into the structure maps by deconvolution processing with the structure resolution enhanced up to the information limit of the microscope, or further, for perfect crystals, to the electron diffraction limit by subsequently combining the corrected electron-diffraction data and utilizing the structure analysis methods developed in X-ray crystallography, and it becomes possible to recognize atoms with different atomic weights by analyzing the image-contrast change with the sample thickness, etc. The derivation of the image-contrast theory, the principle and functions of the developed image-analysis methods are demonstrated. Typical examples of applications to the ab initio crystal-structure determination and studies of crystal defects at atomic level are given. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim