STEM, an electron beam is scanned
over a defined area of the sample. The beam can be localized
a certain point in the image and used to measure an EDX and/or
EEL spectrum there. Moreover, line
scans and mappings can be obtained by this powerful technique.
Example: AuPd Particles on Titanium Oxide
Metal nanoparticles dispersed on titanaia are recognizable in the Z-contrast image as bright patches. To
solve the question whether the metal particles consist of an AuPd
alloy or of the separated au and Pd nanoparticles,
EDXS spot analyses were performed. EDX spectra obtained at the positions
marked in the HAADF-STEM image show the characteristic signals of both metals - even for ca. 1 nm nanoparticles (point 2) - and thus prove
the presence of an alloy.
Characterization of AuPd Nanoparticles by Probe-Corrected Scanning Transmission Electron Microscopy and X-Ray Absorption Spectroscopy
F. Krumeich, S. Marx, A. Baiker, R. Nesper, Z. anorg. allg. Chem. 637 (2011) 875-881