Transmission electron microscopy ( TEM ) is a microscopy technique in
which a beam of electrons is transmitted through a specimen to form an image.
The specimen is most often an ultrathin section less than 100 nm thick or a
suspension on a grid. An image is formed from the interaction of the electrons
with the sample as the beam is transmitted through the specimen. The image is
then magnified and focused onto an imaging device, such as a fluorescent
screen, a layer of photographic film, or a sensor such as a scintillator
attached to a charge-coupled device.
Transmission electron microscopes are capable of imaging at a significantly
higher resolution than light microscopes, owing to the smaller de Broglie
wavelength of electrons.