The Microscopy group at the Helmholtz-Zentrum Berlin (HZB) specializes in the development and application of advanced X-ray microscopy, X-ray tomography and X-ray optics for the 10-nm scale characterization of the nanostructure, chemical nature, and composition of materials with high energy resolution. This world-class facility is comprised of a unique combination of state-of-the-art X-ray microscopy instruments, in-house X-ray diffractive optical development and staff members with expertise in microscopy, physics, biophysics and chemistry to address national needs and technical challenges that impact materials, energy and life sciences.
The full-field Transmission X-ray Microscope (TXM) is installed on an undulator beamline (U41-TXM) at HZB where it produces world leading high resolution images of thick biological specimens. Resolutions better than 30 nm have already been achieved for biological specimens and the resolution is being improved towards 10 nm via the development of better zone plates. Other developments include sample changing facilities, exploitation of different contrast methods and the correlation of the images with those from light and electron microscopy.
Facilities for cryogenic preparation of cells, acquisition of high resolution tomograms at cryo-temperatures and data processing and analysis software for producing and examining tomographic reconstructions from the data are provided.
Although the acquisition of a single X-ray tomogram can take less than one hour, a considerable amount of time is required in examining a large number of samples both to find the best preparation procedures and to obtain statistically significant results. Several days (2-6) per visit are typically required, with the option of splitting the beamtime awarded into multiple visits to allow analysis of the initial results between visits in order to optimise sample preparation techniques.
The beamline shares the undulator with other experimental end stations, operating 50% of the time. XI users are supported by a principal scientist, a beamline scientist and a support scientist. Due to the nature of the instrument users are provided with support for the entire duration of their experiment. The beamline is operated by the X-ray microscopy group in the institute Soft Matter and Functional Materials.
Fig.1: X-ray optical setup of the full-field TXM with tomography stage for flat sample holders. The sample is imaged to high magnification by the zone plate objective into the image plane and recorded by a two dimensional 1340 × 1300 pixel CCD detector. Lower: Photographs of components of the TXM (from left: condenser stage, tomography stage, cryo holder, sample holder and zone plate objective).