Deeper insights with X rays
X ray microscope at BESSY II allows a physical resolution as low as ten nanometres
Since 2003 the Microscopy Research Group at the Institute of Soft Matter and Functional Materials of the Helmholtz-Zentrum Berlin (HZB) has been working on high resolution imagery with X rays. Today, one of the world’s most modern X ray microscopes can be found at the electron storage ring BESSY II in Adlershof. A source of synchrotron radiation, BESSY II generates an intense bundle of X rays with a physical resolution as low as ten nanometres.
Although electron microscopes can depict even smaller structures, X ray microscopes offer many advantages. An electron microscope penetrates the sample material only to a depth less than one micrometre. A typical biological cell, however, is about ten micrometres thick, and the soft X rays generated by BESSY II penetrate whole cells. “Just as computed tomography can depict a head in three dimensions, we can do the same with the internal structures of a single cell,” explained Gerd Schneider, Head of the Microscopy Research Group at the HZB.
An electron microscope contains a vacuum, so biological samples must undergo complex preparations. For analyses in an X ray microscope, tissue need only be shock frozen. A light microscope, for instance, can then locate stains marking certain proteins in a cell, and a high resolution X ray microscope can analyse the cellular structure of this protein, both on the one and the same cell. This so called correlative microscopy opens up new insights into the internal structure and the function of cells.
Not only the morphological structures, also the spatial distribution of key biological elements like phosphorus or sulphur can be rendered visible in the form of their characteristic X ray fluorescence. The high energy resolution in an X ray microscope can even depict the distribution of chemical bonding states thanks to near edge spectroscopy.
Not only the life sciences, also materials and energy research benefit from X ray microscopy. For instance, researchers at the HZB, in cooperation with the Department of Physics at Humboldt-Universität zu Berlin, analysed the structures of organic LEDs. At present, the X ray microscope has been put out of operation for modifications. Ideas have been put forward for further cooperation projects with Humboldt-Universität institutes, e.g. the Integrative Research Institute for the Sciences (IRIS).
By Andreas Heins for Adlershof Special