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The scientific aims outlined in the proposal for the VerSoX beamline are very diverse and include studies of heterogeneous catalysts, pharmaceuticals and biomaterials under realistic conditions, environmental and space science studies on liquids and ices, heritage conservation, and the study of electronic and photonic materials.
A common feature to all proposed studies is an interest in the chemical nature and composition of the near-surface regions of the samples, which are to be characterized using soft X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (NEXAFS/XANES).
They also have in common that they do not need extreme energy resolution or photon flux (in fact, many of the samples are extremely beam-sensitive), however they require non-standard sample environments and detection techniques, which are not usually found or possible at standard soft X-ray beamlines of 3rd generation synchrotron sources.
B07-C branchline: Ambient Pressure XPS End Station (AP-XPS)
In particular, the capability of performing XPS and NEXAFS experiments under near-ambient pressures (up to circa 100 mbar) will enable studying the surface composition of heterogeneous catalysts under working conditions as opposed to conventional ex situ characterisation, characterisation of biological and pharmaceutical samples under equilibrium water-vapour conditions (32 mbar at RT; 60 mbar at 36ºC), and direct spectroscopy of surfaces of liquids (liquid jets or troughs), which offers insight into the atmospheric chemistry of aerosols.
B07-B branchline: NEXAFS / UHV XPS End Station
Other samples, such as those related to heritage conservation and polymeric electronic materials do not require such high ambient pressures but are still often incompatible with ultra-high vacuum requirements due to outgasing. Users studying this kind of samples are often not experienced synchrotron users and want to screen relatively large numbers of samples. Therefore, the second branchline (B) of the beamline will be equipped with an endstation with moderate vacuum restrictions to samples. Automated sample manipulation for high throughput will also enable automatic screening of samples.
A third scientific aim is to facilitate the development of new or less common detection techniques for soft X-ray absorption spectroscopy, such as X-ray fluorescence, optical luminescence and the combination with scanning probe techniques. The former techniques enable the pressure limits to be pushed even higher than what is possible with electron-based detection methods, such as Auger yield or partial yield detection, and even allowing the study of molecules in solution. In addition, luminescence detection enables spatial resolution at the level of optical microscopy (~µm), whereas scanning probe detection would push the limits of spatial resolution down to the nm range. To this end the beamline will offer the possibility to attach small user-built endstations to use new detection devices.
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