Electron Microscopy

  • Momentum resolved STEM

    What we do

    We investigate our samples using high-energy electron beams to obtain images with resolution down to the atom scale. We focus on the development of quantitative methods for electron microscopy.

  • comparison of different inputs

    What we do

    We investigate our samples using high-energy electron beams to obtain images with resolution down to the atom scale. We focus on the development of quantitative methods for electron microscopy.

  • beam electron diffraction patterns

    What we do

    We investigate our samples using high-energy electron beams to obtain images with resolution down to the atom scale. We focus on the development of quantitative methods for electron microscopy.

  • Electrical Polarization

    What we do

    We investigate our samples using high-energy electron beams to obtain images with resolution down to the atom scale. We focus on the development of quantitative methods for electron microscopy.

Electron Microscopy

We use transmission electron microscopy (TEM) to investigate the atomic structure and composition of nanomaterials. In the high-resolution TEM (HRTEM) mode the whole region of interest of our specimen is illuminated with the electron beam and the image is formed with the objective lens and further magnifying lenses. In the Scanning TEM (STEM) mode, the electron beam is focused to a diameter down to 50 pm. The focused beam is scanned over the specimen and scattered electrons are detected with different detectors. Images are formed by plotting the detector signal at each scan position.  The composition of the specimen is measured with energy dispersive X-ray analysis (EDX) and energy loss spectroscopy (EELS). Electron tomography yields the 3D structure of our specimen.

What kind of result do I get?

The high-resolution TEM and STEM images show the atomic structure of the specimen projected along the electron beam direction. The images reveal the crystal structure, dislocations and stacking faults. The positions of atom columns are measured with an accuracy of a few picometers. Distances between atom columns give information on the strain distribution in our specimen. In the STEM mode, using the high-angle annular dark field (HAADF) detector, the brightness of an atom column increases with the atomic number, so that we can distinguish different elements in the images. An atom hit by the electron beam emits a characteristic X-ray spectrum. Its measurement in STEM allows 2D elemental mapping, detecting elements even at small concentrations below 1%.

Area responsible

Prof. Dr. rer-nat. Andreas Rosenauer

Service Electron Microscopy

Application Scientist

Dr. Marco Schowalter


MAPEX Center for Materials and Processes
University of Bremen

Otto-Hahn Allee 1, D-28359 Bremen
Phone: +49 421 218 62263
Email: schowalter@ifp.uni-bremen.de


Dr. Thorsten Mehrtens


MAPEX Center for Materials and Processes
University of Bremen

Otto-Hahn Allee 1, D-28359 Bremen
Phone: +49 421 218 62273
Email: mehrtensprotect me ?!ifp.uni-bremenprotect me ?!.de

Our key instruments

FEI Titan picture

FEI TITAN 80/300
Image corrected (scanning) transmission electron microscope

  • resolution 80 pm in TEM and 130 pm in STEM
  • EDX, EELS, Möllenstedt-Dücker biprism
  • Tomography holder
mehr
Thermo Fischer picture

Thermo Fisher  SPECTRA 30/300
Probe corrected (scanning) transmission electron microscope

  • STEM resolution 50 pm
  • X-FEG, Monochromator
  • Electron Microscope Pixelated Array Detector (EMPAD)
    (direct electron detector with 1000 frames per second)
  • Super-X EDS detector
  • On-axis 360° rotation tomography holder
  • dual-axis tomography holder
mehr
electron scanning microscope

FEI Nova 200 NanoLab
Scanning electron microsope with focused Ga-ion Beam

  • Preparation of TEM samples
  • SEM resolution 1-2 nm
  • acceleration voltage 2 kV – 30 kV
  • probe current 2.5 pA – 37 nA
  • Platinum metal deposition

More available instruments

More information about the instrumentation available at MAPEX and MAPEX-CF can be found in the Instrument Database of the MAPEX Center for Materials and Processes.

A click on the logo will lead you to the database.

Research Highlights

Picture
Electron Microscopy|

Angle-dependence of ADF-STEM intensities for chemical analysis of InGaN/GaN

 Tim Grieb, Florian F.Krause, Knut Müller-Caspary, Jan Philipp Ahl, Marco Schowalter, Oliver Oppermann, Joachim Hertkorn, Karl Engl, Andreas Rosenauer

Ultramicroscopy (2022) 238, 113503

https://doi.org/10.1016/j.ultramic.2022.113535

In this paper we perform angular resolved annular-dark field…


Picture
Electron Microscopy|

Towards the interpretation of a shift of the central beam in nano-beam electron diffraction as a change in mean inner potential

Christoph Mahr, Tim Grieb, Florian F.Krause, Marco Schowalter, Andreas Rosenauer

Ultramicroscopy (2022) 236, 113503

https://doi.org/10.1016/j.ultramic.2022.113503

The measurement of electric fields in scanning transmission electron microscopy (STEM) is a highly investigated field of research. The…


Image nanoparticle
Electron Microscopy|

Promoting Effect of the Residual Silver on the Electrocatalytic Oxidation of Methanol and Its Intermediates on Nanoporous Gold

Alex Ricardo Silva Olaya, Franziska Kühling, Christoph Mahr, Birthe Zandersons, Andreas Rosenauer, Jörg Weissmüller, and Gunther Wittstock

ACS Catal. 2022, 12, 8, 4415–4429

https://doi.org/10.1021/acscatal.1c05160

Nanoporous gold (NPG) obtained by dealloying Ag75Au25 with an overall residual Ag…


Aktualisiert von: MAPEX