Ultraviolet

UVultraviolet lightultraviolet radiationUV lightUV radiationUVBultra-violetUVAUV-Bultra violet
Ultraviolet (UV) is electromagnetic radiation with wavelength from 10 nm to 400 nm, shorter than that of visible light but longer than X-rays.wikipedia
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Electromagnetic radiation

electromagnetic waveelectromagnetic waveselectromagnetic
Ultraviolet (UV) is electromagnetic radiation with wavelength from 10 nm to 400 nm, shorter than that of visible light but longer than X-rays.
It includes radio waves, microwaves, infrared, (visible) light, ultraviolet, X-rays, and gamma rays.

Light

visible lightvisiblelight source
Ultraviolet (UV) is electromagnetic radiation with wavelength from 10 nm to 400 nm, shorter than that of visible light but longer than X-rays.
Visible light is usually defined as having wavelengths in the range of 400–700 nanometers (nm), or 4.00 × 10 −7 to 7.00 × 10 −7 m, between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths).

Sunlight

sunshinesolar radiationnatural light
UV radiation is present in sunlight, and contributes about 10% of the total electromagnetic radiation output from the Sun.
Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light.

Blacklight

black lightWood's lampblack lights
It is also produced by electric arcs and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights.
A blacklight (or often black light), also referred to as a UV-A light, Wood's lamp, or ultraviolet light, is a lamp that emits long-wave (UV-A) ultraviolet light and very little visible light.

Tanning lamp

Sun-tanning lampstanning devicestanning lamps
It is also produced by electric arcs and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights.
Tanning lamps (sometimes called tanning bulbs in the United States or tanning tubes in Europe) are the part of a tanning bed, booth or other tanning device which produces ultraviolet light responsible for tanning.

Fluorescence

fluorescentfluorescefluoresces
Although long-wavelength ultraviolet is not considered an ionizing radiation because its photons lack the energy to ionize atoms, it can cause chemical reactions and causes many substances to glow or fluoresce.
The most striking example of fluorescence occurs when the absorbed radiation is in the ultraviolet region of the spectrum, and thus invisible to the human eye, while the emitted light is in the visible region, which gives the fluorescent substance a distinct color that can be seen only when exposed to UV light.

Ionizing radiation

ionising radiationradiationnuclear radiation
Although long-wavelength ultraviolet is not considered an ionizing radiation because its photons lack the energy to ionize atoms, it can cause chemical reactions and causes many substances to glow or fluoresce.
Gamma rays, X-rays, and the higher ultraviolet part of the electromagnetic spectrum are ionizing, whereas the lower ultraviolet part of the electromagnetic spectrum and all the spectrum below UV, including visible light (including nearly all types of laser light), infrared, microwaves, and radio waves are considered non-ionizing radiation.

Sunburn

sun burnburnSunburns
For humans, suntan and sunburn are familiar effects of exposure of the skin to UV light, along with an increased risks of skin cancer.
Sunburn is a form of radiation burn that affects living tissue, such as skin, that results from an overexposure to ultraviolet (UV) radiation, usually from the Sun.

Vitamin D

DCalciferol1,25 Dihydroxy vitamin D
However, ultraviolet light is also responsible for the formation of bone-strengthening vitamin D in most land vertebrates, including humans (specifically, UVB).
The major natural source of the vitamin is synthesis of cholecalciferol in the lower layers of epidermis skin through a chemical reaction that is dependent on sun exposure (specifically UVB radiation).

Skin cancer

non-melanoma skin cancerskinskin neoplasm
For humans, suntan and sunburn are familiar effects of exposure of the skin to UV light, along with an increased risks of skin cancer.
Greater than 90% of cases are caused by exposure to ultraviolet radiation from the Sun.

Electromagnetic spectrum

spectrumspectraspectral
The electromagnetic spectrum of ultraviolet radiation (UVR), defined most broadly as 10–400 nanometers, can be subdivided into a number of ranges recommended by the ISO standard ISO-21348:
This frequency range is divided into separate bands, and the electromagnetic waves within each frequency band are called by different names; beginning at the low frequency (long wavelength) end of the spectrum these are: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays at the high-frequency (short wavelength) end.

Photodiode

phototransistorphotodiodespinned photodiode
Ultraviolet can be detected by suitable photodiodes and photocathodes, which can be tailored to be sensitive to different parts of the UV spectrum.
Photodiodes are similar to regular semiconductor diodes except that they may be either exposed (to detect vacuum UV or X-rays) or packaged with a window or optical fiber connection to allow light to reach the sensitive part of the device.

Oxygen

OO 2 molecular oxygen
Vacuum UV, or VUV, wavelengths (shorter than 200 nm) are strongly absorbed by molecular oxygen in the air, though the longer wavelengths of about 150–200 nm can propagate through nitrogen.
Another form (allotrope) of oxygen, ozone, strongly absorbs ultraviolet UVB radiation and the high-altitude ozone layer helps protect the biosphere from ultraviolet radiation.

Ultraviolet germicidal irradiation

UV irradiationultraviolet disinfectionultraviolet light
Ultraviolet germicidal irradiation (UVGI) is a disinfection method that uses short-wavelength ultraviolet (UV-C) light to kill or inactivate microorganisms by destroying nucleic acids and disrupting their DNA, leaving them unable to perform vital cellular functions.

Extreme ultraviolet

EUVXUVextreme UV
Extreme ultraviolet radiation (EUV or XUV) or high-energy ultraviolet radiation is electromagnetic radiation in the part of the electromagnetic spectrum spanning wavelengths from 124 nm down to 10 nm, and therefore (by the Planck–Einstein equation) having photons with energies from 10 eV up to 124 eV (corresponding to 124 nm to 10 nm respectively).

Infrared

IRnear-infraredinfra-red
He called them "oxidizing rays" to emphasize chemical reactivity and to distinguish them from "heat rays", discovered the previous year at the other end of the visible spectrum. The terms "chemical rays" and "heat rays" were eventually dropped in favor of ultraviolet and infrared radiation, respectively.
Of this energy, 527 watts is infrared radiation, 445 watts is visible light, and 32 watts is ultraviolet radiation.

Circular dichroism

CDcircular dichroism spectroscopyhelicity
Significant examples include 193 nm photolithography equipment (for semiconductor manufacturing) and circular dichroism spectrometers.
Most notably, UV CD is used to investigate the secondary structure of proteins.

Victor Schumann

Schumann
The discovery of the ultraviolet radiation with wavelengths below 200 nm, named "vacuum ultraviolet" because it is strongly absorbed by the oxygen in air, was made in 1893 by the German physicist Victor Schumann.
Victor Schumann (21 December 1841 – 1 September 1913) was a physicist and spectroscopist who in 1893 discovered the vacuum ultraviolet.

Ozone layer

stratospheric ozoneozoneozone shield
The shorter bands of UVC, as well as even more-energetic UV radiation produced by the Sun, are absorbed by oxygen and generate the ozone in the ozone layer when single oxygen atoms produced by UV photolysis of dioxygen react with more dioxygen.
The ozone layer or ozone shield is a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet radiation.

Extreme Ultraviolet Explorer

EUVEEUVE satelliteExtreme UltraViolet Explorer Satellite
See also the Extreme Ultraviolet Explorer (EUVE) satellite.
With instruments for ultraviolet (UV) radiation between wavelengths of 7 and 76 nm, the EUVE was the first satellite mission especially for the short-wave ultraviolet range.

Photodissociation

photolysisphotodecompositionphotolytic
The shorter bands of UVC, as well as even more-energetic UV radiation produced by the Sun, are absorbed by oxygen and generate the ozone in the ozone layer when single oxygen atoms produced by UV photolysis of dioxygen react with more dioxygen.
Since a photon's energy is inversely proportional to its wavelength, electromagnetic waves with the energy of visible light or higher, such as ultraviolet light, x-rays and gamma rays are usually involved in such reactions.

Radiation

radiologicalradioactiveradiative
The terms "chemical rays" and "heat rays" were eventually dropped in favor of ultraviolet and infrared radiation, respectively.
Ionizing UV therefore does not penetrate Earth's atmosphere to a significant degree, and is sometimes referred to as vacuum ultraviolet.

Optoelectronics

optoelectronicoptronicsopto-electronics
The same terms may also used in other fields, such as cosmetology, optoelectronic, etc. - the numerical value of the boundary between hard/soft even within similar scientific fields do not necessarily coincide; for example one applied physics publication used a boundary of 190 nm between hard and soft UV regions.
In this context, light often includes invisible forms of radiation such as gamma rays, X-rays, ultraviolet and infrared, in addition to visible light.

Radiometer

radiometersinfrared radiometerradiation detector
Spectrometers and radiometers are made for measurement of UV radiation.
Generally, a radiometer is an infrared radiation detector or an ultraviolet detector.

Black-body radiation

blackbody radiationblack body spectrumblackbody spectrum
Very hot objects emit UV radiation (see black-body radiation).
When the body appears white, it is emitting a substantial fraction of its energy as ultraviolet radiation.