Research objectives and content
The advantage of electron microscopy over diffraction techniques is that the phase information is preserved in the images. Much research is currently being done to extract this infonnation (e.g. by electron holography) but the interpretation in te of specimen structure is still somewhat limited. The two main aims of this project (ffe (i) to explore the possibilities of a n technique of interpreting the phase information available in conventional high resolution electron microscope images and to improve the understanding of electron propagation of sub-nanometer probes in scanning transmission electron microscopy. The first part will focus on two materials science problems: (i) the characterisation of the surface structure of nanocrystal and (ii) the measurement of displacement fields around precipitates. More generally, the aim is to compare such results with experimentally more demanding phase retrieval approaches such as holography, defocus variation or ptychography. The second part of the project will have implications for conventional and scanning transmission electron microscope image interpretation. Furthermore, the intention is to make definite statements about the highest resolution attainable in future electron microscopy, which is interpretable in terms of specimen structure and the best technique to use for solving practical materials science problems.
Training content (objective, benefit and expected impact)
I will gain experience about several areas in electron microscopy which I have not worked on yet (specimen prepa ation, conventional high-resolution transmission electron microscopy, conventional diffraction contrast imaging, microanalysis); the work at CECM with its material science background will give me a perspective on practical problems which are of industrial relevance. I will be able to complement my theoretical knowledge by insights into typical material science problems, which I would like to use in order to design new techniques for solving practical, pertinent questions.
Links with industry / industrial relevance (22)
Both the appraisal of current quantitative techniques and the interpretation of interpretable (elastic and inelastic) image resolution as a function of instrumental parameters as intended in this project is of great importance for electron microscope manufacturers.