changed (e.g., from bright to dark), simply by changing the focus position. The
possible signals that may be connected to a scanning transmission electron microscope are shown schematically in Figure 12.20.
Figure 12.19 Electron micrograph of a singlelayer graphene using monochromated
C s -corrected high-resolution transmission
electron microscope at 80 kV acceleration
voltage. It is important to realize the visibility of
every single atom in the graphene layer; the
distance between two atoms in the hexagons is
0.142 nm. (Reproduced with permission by FEI
Company; www.fei.com).
scanning
electron beam
backscattered
electron detector
X-ray
detector
high-angle
annular
dark-field
detector
annular
dark-field
detector
bright-field
detector
specimen
Figure 12.20 System of detectors in connection with a scanning transmission electron microscope.
12.4 Electron Microscopy j357