Eberhard Umbach1, Thomas Schmidt1, Helder Marchetto2, Ulrich Groh1, Rainer Fink3, and the SMART collaboration
1Experimentelle Physik II, Universität Würzburg, D-97074 Würzburg, Germany
2Fritz-Haber-Institut der Max-Planck Gesellschaft, D-14195 Berlin, Germany
3Physikalische Chemie II, Universität Erlangen, D-91058 Erlangen, Germany
It is a dream of surface science to apply sophisticated surface methods, such as Low Energy Electron Diffraction, X-ray Photoemission, Angle-resolved UV Photoemission, Photoelectron Diffraction, X-ray Absorption, and X-ray induced Auger Spectroscopy, with high spatial resolution and to combine them with microscopic techniques. The development of such instruments, called micro-spectro-scopes (scanning instruments) or spectro-microscopes (imaging instruments), has lead to numerous successful approaches which are called Low Energy Electron Microscopes (LEEM) or (X-ray) Photoelectron Emission Microscopes (X-PEEM) and are commercially available today. The heart of these instruments is usually a simple low-energy EM consisting of objective and projective lens systems and a 2-dim detector. However, due to chromatic and spherical aberrations these instruments are limited in their spatial and energy resolution.
A collaboration of several groups from universities, a Max-Planck-Institute, the Zeiss company, and BESSY has designed and built a new type of spectro-microscope that combines a "normal" LEEM/PEEM instrument with aberration corrections (both, chromatic and spherical simultaneously) and energy resolution using an imaging energy filter. The instrument is installed at BESSY II and uses x-ray or UV photons and electrons as sources. Theoretically, a spatial resolution of 0.5 nm at an energy resolution of less than 100 meV is achievable at more than a hundred times higher transmission compared to conventional LEEM/PEEM instruments due to a large acceptance angle. This instrument called SMART has been developed in three stages with experiments after completion of each stage and is now in the final phase of testing and commissioning. The concept, the technical realization, and the present achievements will be reported.
The SMART allows to combine nearly simultaneously various electron microscopy techniques (e.g. LEEM, PEEM, X-PEEM, MEM) with various high-resolution electron spectroscopy and electron diffraction techniques from small sample spots (e.g. nano-XPS, -ARUPS, -XAS, -LEED). First experiments on the growth properties and growth dynamics of organic thin films, their dependence on the substrate and substrate morphology, the molecular orientation, and the internal structure of microcrystallites of organic molecules show the potential of the instrument and will be presented in the talk.
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