Research with coherent X-rays has experienced a tremendous boost in the last decade, as sources with considerable coherent photon flux have become available. The MAX IV 3 GeV ring will provide a very high average coherent flux, especially towards longer wavelengths (lower photon energy). This is an ideal situation for imaging applications built around the use of spatially coherent light waves: coherent imaging and scanning microscopy with soft X-rays. These techniques produce microscopic images of a sample, which at the same time can hold chemical, electronic, magnetic and/or structural information, depending on the details of the experiment.
The beamline will have two branchlines: one for scanning transmission microscopy (STXM) & ptychography where thin samples (eg., 0.1 - 5 micron) are raster scanned with a monochromatic beam focused through a zone plate lens. It enables nanoscale imaging with a unique combination of contrast mechanism, interaction cross section, spatial resolution and relatively low sample damage. Atomic and chemical sensitivity is provided via the absorption resonances and their fine structure allowing not only to distinguish, e.g., Fe from Co, but also Fe2+ from Fe3+. Furthermore, magnetic moments or bond orientation can provide contrast, enabling a variety of applications ranging from materials science to life and environmental science.
The second branch line will be dedicated to Coherent X-ray Imaging (CXI) techniques, where a specimen is typically imaged without X-ray “lenses”. These coherent scattering based approaches have a higher freedom with respect to sample environments (temperature, magnetic or electric fields) compared to more standard X-ray microscopy, and as such the end station will have a modular character. Several techniques such as coherent diffraction imaging, holography and resonant soft x-ray scattering have been established in recent years and are increasingly used for imaging e.g. in nanoscale (magnetic) materials and even life sciences.
|Techniques||Scanning Transmission X-ray Microscopy (including fluorescence), Ptychography, Fourier Transform Holography, Resonant Soft X-ray Scattering|
|Beam Size||Diameter: 10-100 nm (STXM/Ptycho), 20 μm (CXI)|
|Energy Range||275 – 2500 eV with full polarization control|
|Time Scales||ms to s per point/shot, full (fluorescence) spectroscopy scans up to hour(s)|
|Samples||Biology, Magnetism, Life- and Materials science|