9. Scanning Electron Nanodiffraction and Diffraction Imaging

This chapter describes electron nanodiffraction and its use for structural imaging and analysis. The chapter is organized into five sections. The first section contains an introduction to electron nanodiffraction and diffraction imaging and the motivations for developing these techniques. Section 9.2 covers different electron nanodiffraction techniques and their implementation. It is followed by a discussion on the information that can be obtained from electron nanodiffraction and the theory behind it. In outlining the theory for electron nanodiffraction in Section 9.3, we first rely on the kinematical theory to give a conceptual foundation for electron nanodiffraction. The treatment of the kinematical theory is then followed by the well-developed electron multiple scattering theory for CBED of medium to thick crystals. The kinematical theory can be used for both crystalline and noncrystalline atomic structures, while the theory for CBED is largely limited to crystals or crystals with certain types of defects. For the treatment of electron multiple scattering of arbitrary structures, we included a description of the multi-slice method, which is a numerical method often used for electron diffraction simulations. The description of the electron nanodiffraction techniques in Section 9.2 and theory in Section 9.3 are followed by a few application examples in Section 9.4. We focus on the applications of SEND for imaging strain, nanostructures, and defects. The application examples given here serve to highlight the potential of SEND rather than a complete review of electron nanodiffraction applications. We also provide the experimental details in Section 9.4 to give some ideas of what it takes to do SEND. The chapter is finished with a conclusion.