In environmental scanning electron microscopy (ESEM) high pressure applications have become increasingly important. Using this method makes it possible to study wet or biological samples without time consuming sample preparation and potential artefacts from this preparation. Unfortunately, the applications were limited by poor image quality. At the FELMI-ZFE we identified and improved crucial elements so that the image qualities at high pressures of a FEI Quanta 600 (field emission gun) and a FEI Quanta 200 (thermionic gun) were considerably improved by optimizing the pressure limiting system and the secondary electron (SE) detection system.
At the Fritz-Haber-Institute Manfred Nachtnebel met international colleagues who are doing research in the same field. Together they want to find other possibilities how to use the improvements for in situ analyses. For two weeks they concentrated on the hydrogen production during heating experiments. Therefore the scientists combined their expertise in in situ analyses: the FHI’s know-how (a laser heating stage, a mass spectrometer and the possibility to use specific gas compositions) and the Graz ZFE’s special equimpment (a special detector and pressure limiting system to perfom experiments under higher pressure than in conventional ESEMs) made it possible to perform heating experiments in a more realistic scenario. For the first time, the scientists took images of catalytical processes between 700 Pa and 1200 Pa. They observed structural changes of surfaces and were able to overcome the pressure gap which was not possible with the standard system due to physical restraints.
The Fritz-Haber-Institute of the Max-Planck-Society was founded in 1911 as the Kaiser-Wilhelm Institute for Physical Chemistry and Electrochemistry and in 1953 it was incorporated in the Max Planck Society and simultaneously renamed for its first director, Fritz Haber. Their main focus concerning ESEM is on in situ analyses of catalytic processes (e.g. graphene growth on heated copper sample). With the optimized system these experiments can be done at higher pressure which enables new growth mechanisms and can result in better understanding of catalytic processes.
Want to know more?
Fritz-Haber-Institute of the Max-Planck-Society
How to improve Environmental Electron Scanning Microscopes: Recap on the previous visit to Berlin
High-quality imaging in environmental scanning electron microscopy – optimizing the pressure limiting system and the secondary electron detection of a commercially available ESEM
H. Fitzek, H. Schröttner, J. Wagner, F. Hofer, J. Rattenberger