Editing Electromagnetic spectrum (section)

=== Infrared radiation ===
{{Main|Infrared radiation}}
The [[infrared]] part of the electromagnetic spectrum covers the range from roughly 300&nbsp;GHz to 400&nbsp;THz (1&nbsp;mm – 750&nbsp;nm). It can be divided into three parts:<ref name="em-spectrum"/>
* '''Far-infrared''', from 300&nbsp;GHz to 30&nbsp;THz (1&nbsp;mm – 10 μm). The lower part of this range may also be called microwaves or terahertz waves. This radiation is typically absorbed by so-called rotational modes in gas-phase molecules, by molecular motions in liquids, and by [[phonons]] in solids. The water in Earth's atmosphere absorbs so strongly in this range that it renders the atmosphere in effect opaque. However, there are certain wavelength ranges ("windows") within the opaque range that allow partial transmission, and can be used for astronomy. The wavelength range from approximately 200 μm up to a few mm is often referred to as [[Submillimetre astronomy]], reserving far infrared for wavelengths below 200 μm.
* '''Mid-infrared''', from 30&nbsp;THz to 120&nbsp;THz (10–2.5 μm). Hot objects ([[black-body]] radiators) can radiate strongly in this range, and human skin at normal body temperature radiates strongly at the lower end of this region. This radiation is absorbed by molecular vibrations, where the different atoms in a molecule vibrate around their equilibrium positions. This range is sometimes called the ''fingerprint region'', since the mid-infrared absorption spectrum of a compound is very specific for that compound.
* '''Near-infrared''', from 120&nbsp;THz to 400&nbsp;THz (2,500–750&nbsp;nm). Physical processes that are relevant for this range are similar to those for visible light. The highest frequencies in this region can be detected directly by some types of photographic film, and by many types of solid state [[image sensor]]s for [[infrared photography]] and videography.