Data Sheet

The Tyndall Effect
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Atomic Force Microscopy
In this technology, a fine measuring tip is computer-guided along a surface a few nanometers
above the sample. At this tiny distance, certain mutual reactions such as the van der Waals
forces arise between the atoms of the measuring tip and the atoms and molecules of the
object under investigation.
Depending on the nature of the surface, these forces can be stronger or weaker, and they will
therefore deflect the measuring tip to varying degrees — in other words, they will cause the
tip to move up or down by a few nanometers. These tiny movements can be measured and
recorded to produce a precise image of the object’s surface. An atomic force microscope can
produce resolutions of up to 0.1 nm — allowing even individual atoms to be shown!
Scanning Electron Microscopy
Scanning electron microscopes (SEM) scan the studied object “line by line” with a fine
electron beam. To do that, the object’s surface must be electrically conductive. The electron
beam causes electrons on the sample surface to be released. These so-called secondary
electrons are captured by a detector brought above and to the side of the sample. Scanning
electron microscopes are often used to study surfaces, since they can create images with
excellent depth of sharpness.
Individual atoms in a calcite crystal
Structure of a butterfly’s wing
SEM images of a fly’s eye
0 2 nm10 2 nm10 2 nm1
Red blood cells
0 30 µm15
0 200 µm100 0 50 µm25 0 40 µm20 0 10 µm5