Gerd Schneider receives a professorship for "X-ray microscopy" at Humboldt-Universität zu Berlin
Prof. Dr. Gerd Schneider becomes a full professur for x-ray microscopy at the Humboldt University Berlin and is the head of the HZB group "Microscopy". © WISTA MANAGEMENT GmbH
On 29 April 2015, Gerd Schneider (HZB) accepted the call to a W2-S “X-ray microscopy” professorship at the Department of Physics of Humboldt-Universität zu Berlin. The professorship is associated with heading the workgroup “X-ray microscopy” at the Helmholtz-Zentrum Berlin für Materialien und Energie. With his group, the internationally recognised expert is developing new methods and applications for X-ray microscopy, which delivers crucial information for many scientific disciplines – from material and energy research to the life sciences.
The workgroup of Gerd Schneider operates one of the most advanced X-ray microscopes in the world, which allows spatial resolutions of down to ten nanometres using the “soft” X-ray light from BESSY II.
X-ray microscopy is an indispensable tool for studying materials
X-ray microscopy has decisive advantages over optical and electron microscopy: It allows researchers to observe objects in three dimensions, for example – and that at a very high resolution of 10 nanometres. “While researchers can only observe very thin samples of a maximum of about 0.1-µm thickness under the electron microscope, X-ray microscopy allows you to study entire cells of 10-µm thickness, for example. Compared to modern, super-resolution optical microscopy, which needs stain molecules inside cells to overcome the Abbé resolution limit, X-ray microscopy delivers a direct view to the cellular structures without any staining,” Prof. Gerd Schneider explains. Optical and X-ray microscopy therefore allow the study of whole cells, where correlative optical microscopy of individual cells can localise certain proteins whose distributions can be brought into a structural cellular context using X-ray microscopy.
Since every chemical element has specific X-ray absorption edges, X-ray microscopy can be used to determine the specific elements in the components of a sample. Even chemical bonding states can be clearly imaged using near-edge spectroscopy. Because the elements exhibit characteristic fluorescence under X-ray lights, one can also clearly determine the spatial distribution of extremely low concentrations of elements in a sample. In this way, X-ray microscopy delivers a comprehensive picture of each sample.
Developing high-precision lenses
Achieving the highest possible resolution in X-ray microscopy requires high-precision lenses to focus the X-ray beams. In addition to developing X-ray microscopes, Gerd Schneider’s workgroup has contributed greatly to the advancement of these lenses, known as Fresnel zone plates. Given such 3D X-ray lenses and modern synchrotron sources like BESSY II, great contributions can be made towards answering many scientific questions, from the fundamentals of structural biology to research into modern energy storage solutions.
- Battery research: visualisation of aging processes operandoLithium button cells with electrodes made of nickel-manganese-cobalt oxides (NMC) are very powerful. Unfortunately, their capacity decreases over time. Now, for the first time, a team has used a non-destructive method to observe how the elemental composition of the individual layers in a button cell changes during charging cycles. The study, now published in the journal Small, involved teams from the Physikalisch-Technische Bundesanstalt (PTB), the University of Münster, researchers from the SyncLab research group at HZB and the BLiX laboratory at the Technical University of Berlin. Measurements were carried out in the BLiX laboratory and at the BESSY II synchrotron radiation source.
- New instrument at BESSY II: The OÆSE endstation in EMILA new instrument is now available at BESSY II for investigating catalyst materials, battery electrodes and other energy devices under operating conditions: the Operando Absorption and Emission Spectroscopy on EMIL (OÆSE) endstation in the Energy Materials In-situ Laboratory Berlin (EMIL). A team led by Raul Garcia-Diez and Marcus Bär showcases the instrument’s capabilities via a proof-of-concept study on electrodeposited copper.
- Green hydrogen: A cage structured material transforms into a performant catalystClathrates are characterised by a complex cage structure that provides space for guest ions too. Now, for the first time, a team has investigated the suitability of clathrates as catalysts for electrolytic hydrogen production with impressive results: the clathrate sample was even more efficient and robust than currently used nickel-based catalysts. They also found a reason for this enhanced performance. Measurements at BESSY II showed that the clathrates undergo structural changes during the catalytic reaction: the three-dimensional cage structure decays into ultra-thin nanosheets that allow maximum contact with active catalytic centres. The study has been published in the journal ‘Angewandte Chemie’.