UE49 SMART Beamline

The high flux density beamline is specially designed for the high resolution, aberration corrected spectromicroscope SMART. Located in a low-beta section with a round undulator source the PGM beamline illuminates the specimen surface in the SMART electron microscope with an ideal round beam with high flux density. The wide energy range of 100 to 1800 eV gives access to nearly all relevant XPS peaks and NEXAFS adsorption edges, used for chemical contrast in the photoemission electron microscope to study the local chemical composition on the surface in nanometer range. The variable choice of horizontal, vertical and (left/right) circular polarized light enables the investigation of e.g. molecular orientation in organic films or the magnetization in magnetic domains.

UE49 SMART beamline with microscope in front

Spectro-Microscopy with aberration correction for relevant techniques Station

Spectro-Microscopy with Aberration correction for many relevant Techniques

The instrument is an aberration corrected photo-emission electron microscope equipped with an imaging energy analyzer and installed at the high flux density beamline UE49 SMART. The SMART microscope is the first PEEM, showing successfully the simultaneous compensation for spherical and chromatic aberrations, enabling an outstanding lateral resolution of 2.6 nm (LEEM) and 18 nm (energy filtered XPEEM using W4f XPS peak) together with an increase in transmission by a factor of 6, demonstrated under experimental conditions at BESSY-II.

The multitude of operation modes – microscopy, spectroscopy and diffraction of photo-emitted and reflected electrons – and the variety of methods, e.g.  photoemission electron microscopy (PEEM), energy-filtered XPEEM, NEXAFS-PEEM, LEEM, NEXAFS, XPS, UPS, XMCD, XMLD, photoelectron diffraction (PED), valence band structure mapping, and LEED, allow for a comprehensive characterization of inhomogeneous surfaces and thin films on nanometer scale with a surface sensitivity of only a few atomic layers. Examples are the local chemical composition of metal nano-particles and of structural domains in thin oxide films, the local molecular orientation of inhomogeneous organic films and local band structure measurements of ordered silica films.

Furthermore, the fast direct (i.e. non-scanning) imaging combined with the possibilities to deposit material on the specimen surface in measurement position, to cool or anneal the sample and to expose the surface to reactive gases during operation enable the in-situ and real time study of complex processes like e.g. film growth, alloying, chemical surface reaction, thermal desorption or phase transition on nanometer scale in video rate with chemical and structural contrast.

SMART microscope at UE49 SMART beamline

Methods

• Microscopy:
  Photoelectron EM (PEEM), energy-filtered XPEEM, NEXAFS-PEEM, X-ray Microscopy, LEEM, Hg-PEEM
• Spectroscopy:
  NEXAFS, XPS, UPS, Angular-resolved PES, XMCD, XMLD,
• Diffraction/angular distribution:
  Surface Diffraction, Photoelectron Diffraction (PED), Valence band structure mapping, LEED