With electron tomography (3D-TEM) a 3D-reconstruction is calculated from a series of
TEM images taken at a tilt angle range (tilting range) of +70° to -70°. The reconstruction can
be visualized with contour surfaces that give information about the surface of the sample as
well as with slices through the reconstruction that give detailed information on the interior of
the sample. Electron tomography gives much more information than Scanning Electron
Microscopy (SEM), since SEM gives only information about the surface of a sample. As a
case study, the imaging of silver clusters on zeolite NaY is given. The reconstruction shows
silver particles at the external surface as well as a silver particle in a mesopore of the zeolite
crystallite. It is concluded that 3D-TEM comprises a breakthrough in the characterization of
nano-structured solid catalysts