Quantitative analysis of convergent-beam electron diffraction patterns

Abstract

In recent years, there have been great advances in electron crystallography by quantitative convergent beam electron diffraction (QCBED). From the distribution of dynamical diffraction intensities, QCBED can determine the Fourier components of the crystal potential accurately and completely, enabling direct measurement of phases of crystal structure factors. Given the combination of small probe size in CBED and the high accuracy of the quantitative analysis (e.g. determination of bonding charge distributions in covalent crystals), QCBED is a powerful experimental methods for detection of a small change in the crystal potential of a few nanometer structure (e.g. near grain boundaries/defects).More recently, interest has shifted towards the possibility of the automated matching of experimental and theoretical CBED patterns by optimization for speed and even higher accuracy. In this work, the combined variable matrix algorithm is used to automate the least-squares refinement. The program was tested by calculated intensities randomized with Gaussian distribution as experimental data.