TEM: STEM/ADF-HAADF

Benefit description

Annular dark-field (ADF) imaging is performed using the TEM microscope in scanning mode (STEM). A small electron probe is focused and scanned over the specimen and the elastically scattered electrons are collected on an annular detector at each probe position to provide ADF images. The collection angles on the detector can be adjusted by changing the camera length. At high collection angles (HAADF), only the incoherently scattered electrons reach the detector and the intensity on the images is sensitive to variations in the atomic number of atoms in the sample (chemical Z-contrast). The HAADF detector available is a Model 3000 from the Fischione company. The regions to analyze, the magnification as well as the probe size can be adjusted. The spatial resolution using high resolution STEM conditions is 0.16 nm at the available Tecnai F30 microscope.