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Chemical Physics - Spectro-Microscopy Group
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Detailed Information on the Experiment

The spectro-microscope SMART [1] (Spectro-Microscope with Aberration correction for many Relevant Techniques) has been installed at the BESSY II electron storage ring within a cooperation between the Fritz-Haber-Institute, University of Würzburg (Prof. Umbach), TU Darmstadt (Prof. Rose), TU Clausthal, (Dr. Lilienkamp / Prof. Bauer) and Leo GmbH (now Carl Zeiss NTS GmbH). This microscope combines the technology of the LEEM microscope [2] with an energy resolving omega filter [3] and a corrector system consisting of a magnetic beam separator and a tetrode mirror [4] (see image). Due to the simultaneous compensation for both, the spherical and chromatic aberrations of the electron lens system, the instrument achieves an ultimate lateral resolution of 2 nm (theoretical limit: 0.5 nm) at an energy resolution of 100 meV. At the same time the transmission is increased by two orders of magnitude.

Utilizing different sources (linearly or circularly polarized x-rays, UV-light, electron gun, etc.) the SMART excels as a versatile instrument [5] with a variety of contrast mechanisms by imaging photo-emitted (XPEEM, UV-PEEM) and reflected electrons (LEEM, MEM). Thus it enables the spatially resolved study of morphology, chemical distribution, electronic state, molecular orientation, magnetization, work function, structural properties, atomic steps, etc. Within seconds the instrument can be switched from microscopy to two further modes of operation: (a) laterally resolved spectroscopy from small object areas (nano-XPS, nano-AES, nano-NEXAFS, UPS, etc.) and (b) laterally resolved and energy filtered imaging of angular distributions of the electrons: nano-PED (photoelectron diffraction), Fermi surface/valence band mapping, -LEED (low energy electron diffraction from small object areas), etc.

Possible applications of this instrument are:

  • Real-time observation of organic and inorganic layer growth
  • Imaging of domains of adsorbate layers
  • Termination of polar surfaces
  • Clusters on model catalysts
  • Segregation at defect structures
  • Diffusion/reaction fronts of adsorbates on single crystal surfaces
  • Analysis of microstructured semiconductor surfaces
  • Formation of structures during oxidation
  • Magnetic structures
  • Phase transition etc...

    This project has been funded by the Bundesministerium für Bildung und Forschung (BMBF) under contract number 05 KS4 WWB/4.

    [1] R. Fink et al., "SMART- a planned ultrahigh-resolution spectro-microscope for BESSY II", J. Electr. Spectrosc. Rel. Phen. 84 (1997) 231-250.

    [2] W. Telieps, E. Bauer, Ultramicroscopy 17 (1985) 57; E. Bauer, M. Mundschau, W. Swiech, W. Telieps, Ultramicroscopy 31 (1989) 49; E. Bauer, Surf. Sci. 299/300 (1994) 102

    [3] S. Lanio, H. Rose, D. Krahl, Optik 73 (1986) 56; H. Rose, E. Plies, Optik 40 (1974) 336; D. Krahl, Mat.-Wiss. u. Werkstofftechnik 21 (1990) 84

    [4] H. Rose, D. Preikszas, Optik 92 (1992) 31; D. Preikszas, Dissertation, Darmstadt 1995

    [5] Th. Schmidt et al., "XPEEM with energy-filtering: advantages and first results from the SMART project", Surf. Rev. Lett. 9 (2002) 223-232

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