SXM End Station

Since the effective lateral resolution in a SXM results form the convolution of the diffraction-limited point-spread function with the demagnified image of the source, a good rule of thumb to maximise resolution while keeping a high photon flux is to set the geometrical demagnification of the source roughly equal to the diffraction-limited lateral resolution.

Like other scanning probe techniques, SXM allows simultaneous monitoring of different signals, using appropriate X-rays or electron detectors. Thus simultaneous images of the transmitted X-rays and emitted photons and electrons can be recorded. Scanning instruments are therefore well suited for a combination of imaging and spectromicroscopy. The versatility of the detector setup allows also simultaneous acquisition of different contrast modes including absorption, differential phase and interference contrast, and dark-field imaging. The price to pay for this flexibility is an increased demand on the experimental setup, where the positioning accuracy of the optical element typically requires the use of sophisticated mechanical setups and optical feed-back systems.

Key figures of the I08-SXM end station are:

• Capability to cope with the broad photon energy range of 250-4200 eV by varying working distances of microprobe optics from <1-120 mm and adapting the geometrical demagnification by varyign the distance of secondary source to microprobe forming optic from 1.2-4m;
• Multiple detector geometries including a transmission EMCCD detector for simultaneous acquisition of absorption, differential phase and darkfield images, and a low-energy X-ray fluorescence detector, among others;
• LN2 cryogenic specimen environment including semi-automated specimen transfer system;
• In-situ visible light microscope for specimen investigation prior to the X-ray analysis.