Berlin 2012 – wissenschaftliches Programm

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MI: Fachverband Mikrosonden

MI 2: TEM- and SEM-based material analysis

MI 2.2: Hauptvortrag

Montag, 26. März 2012, 10:15–11:00, EMH 225

Physical foundations of electron diffraction methods in the scanning electron microscope — •Aimo Winkelmann — Max-Planck-Institut für Mikrostrukturphysik, Halle (Saale)

Electron diffraction techniques like Electron Backscatter Diffraction (EBSD) and Electron Channeling Patterns (ECP) are powerful tools for the crystallographic analysis of materials in the scanning electron microscope (SEM). Pronounced improvements in applications of these methods can be expected with quantitative theoretical and experimental access to the physics of the underlying diffraction processes.

It is demonstrated how the Bloch-wave approach of dynamical electron diffraction theory can be applied for the quantitative simulation of the Kikuchi diffraction patterns observed in EBSD and ECP in the SEM. Analogies are drawn to Kikuchi pattern formation in transmission electron microscopy (TEM). By energy-resolved experimental measurements, the correlations between the energy of the elastically and inelastically scattered electrons and their diffraction effects were investigated. It is shown that quasi-elastic nuclear recoil is a central incoherent process relevant for the formation of Kikuchi patterns. Also, under certain conditions, inelastically scattered electrons in the SEM can show more pronounced diffraction effects than the elastic electrons.