A nanoparticle or ultrafine particle is a particle of matter 1 to 100 nanometres (nm) in diameter. The term is sometimes used for larger particles, up to 500 nm, or fibers and tubes that are less than 100 nm in only two directions. At the lowest range, metal particles smaller than 1 nm are usually called atom clusters instead.
TEM (a, b, and c) images of prepared mesoporous silica nanoparticles with mean outer diameter: (a) 20nm, (b) 45nm, and (c) 80nm. SEM (d) image corresponding to (b). The insets are a high magnification of mesoporous silica particle.
Idealized model of a crystalline nanoparticle of platinum, about 2 nm in diameter, showing individual atoms.
Nanostars of vanadium(IV) oxide (VO2) exhibiting a crystal clusters structure resembling that of desert roses
1 kg of particles of 1 mm3 has the same surface area as 1 mg of particles of 1 nm3
An electron microscope is a microscope that uses a beam of electrons as a source of illumination. They use electron optics that are analogous to the glass lenses of an optical light microscope to control the electron beam, for instance focusing them to produce magnified images or electron diffraction patterns. As the wavelength of an electron can be up to 100,000 times smaller than that of visible light, electron microscopes have a much higher resolution of about 0.1 nm, which compares to about 200 nm for light microscopes. Electron microscope may refer to:Transmission electron microscopy (TEM) where swift electrons go through a thin sample
Scanning transmission electron microscopy (STEM) which is similar to TEM with a scanned electron probe
Scanning electron microscope (SEM) which is similar to STEM, but with thick samples
Electron microprobe similar to a SEM, but more for chemical analysis
Ultrafast scanning electron microscopy, version of a SEM that can operate very fast
Low-energy electron microscopy (LEEM), used to image surfaces
Photoemission electron microscopy (PEEM) which is similar to LEEM using electrons emitted from surfaces by photons
A transmission electron microscope from 2002
An image of an ant in a scanning electron microscope
Reproduction of an early electron microscope constructed by Ernst Ruska in the 1930s
Image of Bacillus subtilis taken with a 1960s electron microscope