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.
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 2-D elemental mapping, detecting elements even at small concentrations below 1%.
Prof. Dr. rer-nat. Andreas Rosenauer
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: 澳门皇冠_皇冠足球比分-劲爆体育tensprotect me ?!ifp.uni-bremenprotect me ?!.de
FEI TITAN 80/300
Image corrected (scanning) transmission electron microscope
Thermo Fisher SPECTRA 30/300
Probe corrected (scanning) transmission electron microscope
FEI Nova 200 NanoLab
Scanning electron microsope with focused Ga-ion Beam
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.
