False-color image of the solar corona as seen in deep ultraviolet light at 17.1 nm by the Extreme ultraviolet Imaging Telescope instrument aboard the SOHO spacecraft

An ultraviolet photograph of the Earth taken from the Moon by Apollo 16 astronauts.

Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than soft X-rays. It is so named because the spectrum consists of electromagnetic waves with frequencies higher than those that humans identify as the color violet. Ultraviolet can refer to Ultraviolet radiation. ... UV may refer to: Ultraviolet radiation UV mapping, a 3D modeling technique University of Victoria, Canada University of Vermont, United States University of Virginia, United States ‹ The template below has been proposed for deletion. ... Image File history File links Download high-resolution version (1024x1024, 809 KB)An image taken by the Solar and Heliospheric Observatory (SOHO) spacecrafts EIT instrument showing the corona in deep UV at 17. ... Image File history File links Download high-resolution version (1024x1024, 809 KB)An image taken by the Solar and Heliospheric Observatory (SOHO) spacecrafts EIT instrument showing the corona in deep UV at 17. ... A false color image showing the Chesapeake Bay and the city of Baltimore. ... Sol redirects here. ... This article is about the astronomical term. ... A nanometre (American spelling: nanometer) is 1. ... The Bastille Day Flare at the 19. ... The Solar and Heliospheric Observatory (SOHO) is a spacecraft that was launched on an Atlas IIAS launch vehicle on 2 December 1995 to study the Sun, and began normal operations in May 1996. ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Apollo 16 was the tenth manned mission in the Apollo program and the fifth mission to land on the Moon. ... This box:      Electromagnetic (EM) radiation is a self-propagating wave in space with electric and magnetic components. ... For other uses, see Wavelength (disambiguation). ... The optical spectrum (light or visible spectrum) is the portion of the electromagnetic spectrum that is visible to the human eye. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... Violet (named after the flower violet) is used in two senses: first, referring to the color of light at the short-wavelength end of the visible spectrum, approximately 380–420 nanometres (this is a spectral color). ...

UV light is typically found as part of the radiation received by the Earth from the Sun. Most humans are aware of the effects of UV through the painful condition of sunburn. The UV spectrum has many other effects, including both beneficial and damaging changes to human health.

Discovery

The discovery of UV radiation was intimately associated with the observation that silver salts darken when exposed to sunlight. In 1801 the German physicist Johann Wilhelm Ritter made the hallmark observation that invisible rays just beyond the violet end of the visible spectrum were especially effective at darkening silver chloride-soaked paper. He called them "de-oxidizing rays" to emphasize their chemical reactivity and to distinguish them from "heat rays" at the other end of the visible spectrum. The simpler term "chemical rays" was adopted shortly thereafter, and it remained popular throughout the 19th century. The terms chemical and heat rays were eventually dropped in favor of ultraviolet and infrared radiation, respectively.^[1] Johann Wilhelm Ritter (1776 - 1810) was a German chemist and physicist. ... Related Compounds Other anions silver(I) fluoride, silver bromide, silver iodide Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references Silver chloride is a chemical compound with the chemical formula AgCl. ... Reactivity refers to the rate at which a chemical substance tends to undergo a chemical reaction in time. ... For other uses, see Infrared (disambiguation). ... For other uses, see Radiation (disambiguation). ...

Origin of term

The name means "beyond violet" (from Latin ultra, "beyond"), violet being the color of the shortest wavelengths of visible light. UV light has a shorter wavelength than that of violet light. For other uses, see Latins and Latin (disambiguation). ... Violet (named after the flower violet) refers to any of a group of reddish blue or bluish purple colors. ... Color is an important part of the visual arts. ...

Subtypes

The electromagnetic spectrum of ultraviolet light can be subdivided in a number of ways. The draft ISO standard on determining solar irradiances (ISO-DIS-21348)^[2] describes the following ranges:

In photolithography, in laser technology, etc., the term deep ultraviolet or DUV refers to wavelengths below 300 nm. "Vacuum UV" is so named because it is absorbed strongly by air and is therefore used in a vacuum. In the long-wave limit of this region, roughly 150-200 nm, the principal absorber is the oxygen in air. Work in this region can be performed in an oxygen free atmosphere, pure nitrogen being commonly used, which avoids the need for a vacuum chamber. For other uses, see Wavelength (disambiguation). ... A nanometre (American spelling: nanometer) is 1. ... Spectrum of a fluorescent black light source. ... A low pressure mercury vapor discharge tube floods the inside of a hood with shortwave UV light when not in use, sterilizing microbiological contaminants from irradiated surfaces. ... Photolithography is a process used in semiconductor device fabrication to transfer a pattern from a photomask (also called reticle) to the surface of a substrate. ... For other uses, see Laser (disambiguation). ... Look up air in Wiktionary, the free dictionary. ... This article is about the chemical element and its most stable form, or dioxygen. ...

See 1 E-7 m for a list of objects of comparable sizes. To help compare different orders of magnitude this page lists lengths between 10-7 and 10-6 m (100 nm and 1 µm). ...

Black light

Main article: Black light

A black light, or Wood's light, is a lamp that emits long wave UV radiation and very little visible light. Commonly these are referred to as simply a "UV light". Fluorescent black lights are typically made in the same fashion as normal fluorescent lights except that only one phosphor is used and the normally clear glass envelope of the bulb may be replaced by a deep-bluish-purple glass called Wood's glass, a nickel-oxide–doped glass, which blocks almost all visible light above 400 nanometers. The color of such lamps is often referred to in the trade as "blacklight blue" or "BLB." This is to distinguish these lamps from "bug zapper" blacklight ("BL") lamps that don't have the blue Wood's glass. The phosphor typically used for a near 368 to 371 nanometer emission peak is either europium-doped strontium fluoroborate (SrB4O7F:Eu2+) or europium-doped strontium borate (SrB4O7:Eu2+) while the phosphor used to produce a peak around 350 to 353 nanometers is lead-doped barium silicate (BaSi2O5:Pb+). "Blacklight Blue" lamps peak at 365 nm. Spectrum of a fluorescent black light source. ... A black light bulb. ...

While "black lights" do produce light in the UV range, their spectrum is confined to the longwave UVA region. Unlike UVB and UVC, which are responsible for the direct DNA damage that leads to skin cancer, black light is limited to lower energy, longer waves and does not cause sunburn. However, UVA is capable of causing damage to collagen fibers and destroying vitamin A in skin.

A black light may also be formed by simply using Wood's glass instead of clear glass as the envelope for a common incandescent bulb. This was the method used to create the very first black light sources. Though it remains a cheaper alternative to the fluorescent method, it is exceptionally inefficient at producing UV light (a mere few lumens per watt) owing to the black body nature of the incandescent light source. Incandescent UV bulbs, due to their inefficiency, may also become dangerously hot during use. More rarely still, high power (hundreds of watts) mercury vapor black lights can be found which use a UV emitting phosphor and an envelope of Wood's glass. These lamps are used mainly for theatrical and concert displays and also become very hot during normal use. As the temperature decreases, the peak of the black body radiation curve moves to lower intensities and longer wavelengths. ...

Some UV fluorescent bulbs specifically designed to attract insects for use in bug zappers use the same near-UV emitting phosphor as normal blacklights, but use plain glass instead of the more expensive Wood's glass. Plain glass blocks less of the visible mercury emission spectrum, making them appear light blue to the naked eye. These lamps are referred to as "blacklight" or "BL" in most lighting catalogs.

Ultraviolet light can be also generated by some light-emitting diodes.

Natural sources of UV

The Sun emits ultraviolet radiation in the UVA, UVB, and UVC bands, but because of absorption in the atmosphere's ozone layer, 98.7% of the ultraviolet radiation that reaches the Earth's surface is UVA. (Some of the UVB and UVC radiation is responsible for the generation of the ozone layer.) Sol redirects here. ... Air redirects here. ... The ozone layer is a layer in Earths atmosphere which contains relatively high concentrations of ozone (O3). ...

Ordinary glass is partially transparent to UVA but is opaque to shorter wavelengths while Silica or quartz glass, depending on quality, can be transparent even to vacuum UV wavelengths. Ordinary window glass passes about 90% of the light above 350 nm, but blocks over 90% of the light below 300 nm.^[3][4][5] This article is about the material. ... A sphere manufactured by NASA out of fused quartz for use in a gyroscope in the Gravity Probe B experiment. ...

The onset of vacuum UV, 200 nm, is defined by the fact that ordinary air is opaque below this wavelength. This opacity is due to the strong absorption of light of these wavelengths by oxygen in the air. Pure nitrogen (less than about 10 ppm oxygen) is transparent to wavelengths in the range of about 150–200 nm. This has wide practical significance now that semiconductor manufacturing processes are using wavelengths shorter than 200 nm. By working in oxygen-free gas, the equipment does not have to be built to withstand the pressure differences required to work in a vacuum. Some other scientific instruments, such as circular dichroism spectrometers, are also commonly nitrogen purged and operate in this spectral region. Circular dichroism (CD) is a form of spectroscopy based on the differential absorption of left- and right-handed circularly polarized light. ...

Extreme UV is characterized by a transition in the physics of interaction with matter: wavelengths longer than about 30 nm interact mainly with the chemical valence electrons of matter, while wavelengths shorter than that interact mainly with inner shell electrons and nuclei. The long end of the EUV/XUV spectrum is set by a prominent He⁺ spectral line at 30.4nm. XUV is strongly absorbed by most known materials, but it is possible to synthesize multilayer optics that reflect up to about 50% of XUV radiation at normal incidence. This technology has been used to make telescopes for solar imaging; it was pioneered by the NIXT and MSSTA sounding rockets in the 1990s; (current examples are SOHO/EIT and TRACE) and for nanolithography (printing of traces and devices on microchips). In chemistry, valence electrons are the electrons contained in the valence shell of an atom, and which are likely to participate in a chemical reaction through bonding with other atoms or molecules. ... General Name, symbol, number helium, He, 2 Chemical series noble gases Group, period, block 18, 1, s Appearance colorless Standard atomic weight 4. ... A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from an excess or deficiency of photons in a narrow frequency range, compared with the nearby frequencies. ... Multilayer optics are optical elements that use interference effects between thin layers of material. ... Fig. ... Sol redirects here. ... Sounding rocket 36. ... The Solar and Heliospheric Observatory (SOHO) is a spacecraft that was launched on an Atlas IIAS launch vehicle on 2 December 1995 to study the Sun, and began normal operations in May 1996. ... Look up Trace in Wiktionary, the free dictionary. ... Nanolithography — or lithography at the nanometer scale — refers to the fabrication of nanometer-scale structures, meaning patterns with at least one lateral dimension between the size of an individual atom and approximately 100 nm. ... An integrated circuit (IC) is a thin chip consisting of at least two interconnected semiconductor devices, mainly transistors, as well as passive components like resistors. ...

Human health-related effects of UV radiation

Beneficial effects

The Earth's atmosphere blocks UV radiation from penetrating through the atmosphere by 98.7%. A positive effect of UVB exposure is that it induces the production of vitamin D in the skin. It has been estimated that tens of thousands of premature deaths occur in the United States annually from a range of cancers due to vitamin D deficiency.^[6] Another effect of vitamin D deficiency is osteomalacia (the adult equivalent of rickets), which can result in bone pain, difficulty in weight bearing and sometimes fractures. Other studies show most people get adequate Vitamin D through food and incidental exposure.^[7] Vitamin D is a fat soluble vitamin that contributes to the maintenance of normal levels of calcium and phosphorus in the bloodstream. ... Osteomalacia is a softening of the bones, resulting from defective bone mineralisation. ...

Many countries have fortified certain foods with Vitamin D to prevent deficiency. Eating fortified foods or taking a dietary supplement pill is usually preferred to UVB exposure, due to the increased risk of skin cancer from UV radiation.^[7] Formed in December of 2004, Fortified began creating and shaping their destiny to becoming what it is now. ... A dietary supplement is intended to supply nutrients, (vitamins, minerals, fatty acids or amino acids) that are missing or not consumed in sufficient quantity in a persons diet. ...

Too little UVB radiation leads to a lack of Vitamin D. Too much UVB radiation leads to direct DNA damages and sunburn. An appropriate amount of UVB (What is appropriate depends on your skin colour) leads to a limited amount of direct DNA damage. This is recognized and repaired by the body. Then the melanin production is increased which leads to a long lasting tan. This tan occurs with a 2 day lag phase after irradiation, but it is much less harmful and long lasting than the one obtained from UVA.

Ultraviolet radiation has other medical applications, in the treatment of skin conditions such as psoriasis and vitiligo. UVA radiation can be used in conjunction with psoralens (PUVA treatment). UVB radiation is rarely used in conjunction with psoralens. In cases of psoriasis and vitiligo, UV light with wavelength of 311 nm is most effective.^{[citation needed]} Not to be confused with alphos, a form of leprosy once called vitiligo. ... PUVA is a Psoralen + UVA treatment. ... Psoralen (also called psoralene) is the parent compound in a family of natural products known as furocoumarins. ... Not to be confused with alphos, a form of leprosy once called vitiligo. ...

Harmful effects

An overexposure to UVB radiation can cause sunburn and some forms of skin cancer. In humans, prolonged exposure to solar UV radiation may result in acute and chronic health effects on the skin, eye, and immune system.^[8] However the most deadly form - malignant melanoma - is mostly caused by the indirect DNA damage (free radicals and oxidative stress). This can be seen from the absence of a UV-signature mutation in 92% of all melanoma.^[9] Health effects, health impacts or health risks are an important consideration in many areas, such as hygiene, pollution studies, workplace safety, nutrition and health sciences in general. ... This article is about the organ. ... A scanning electron microscope image of a single neutrophil (yellow), engulfing anthrax bacteria (orange). ...

UVC rays are the highest energy, most dangerous type of ultraviolet light. Little attention has been given to UVC rays in the past since they are filtered out by the atmosphere. However, their use in equipment such as pond sterilization units may pose an exposure risk, if the lamp is switched on outside of its enclosed pond sterilization unit. Sterilization (or sterilisation) refers to any process that effectively kills or eliminates transmissible agents (such as fungi, bacteria, viruses and prions) from a surface, equipment, foods, medications, or biological culture medium. ...

Ultraviolet photons harm the DNA molecules of living organisms in different ways. In one common damage event, adjacent Thymine bases bond with each other, instead of across the "ladder". This makes a bulge, and the distorted DNA molecule does not function properly.

Ultraviolet (UV) photons harm the DNA molecules of living organisms in different ways. ... Ultraviolet (UV) photons harm the DNA molecules of living organisms in different ways. ... The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... For the similarly-spelled vitamin compound, see Thiamine Thymine, also known as 5-methyluracil, is a pyrimidine nucleobase. ...

Skin

UVA, UVB and UVC can all damage collagen fibers and thereby accelerate aging of the skin. Both UVA and UVB destroy vitamin A in skin which may cause further damage.^[11] In the past UVA was considered less harmful, but today it is known, that it can contribute to skin cancer via the indirect DNA damage (free radicals and reactive oxygen species). It penetrates deeply but it does not cause sunburn. UVA does not damage DNA directly like UVB and UVC, but it can generate highly reactive chemical intermediates, such as hydroxyl and oxygen radicals, which in turn can damage DNA. Because it does not cause reddening of the skin (erythema) it cannot be measured in the SPF testing. There is no good clinical measurement of the blocking of UVA radiation, but it is important that sunscreen block both UVA and UVB. Some scientists blame the absence of UVA filters in sunscreens for the higher melanoma-risk that was found for sunscreen users. ^[12] Erythema is redness of the skin caused by capillary congestion. ... A woman sunbathing A suntanned arm showing browner skin where it has been exposed. ... Immunosuppression is the medical suppression of the immune system. ... Tropocollagen triple helix. ... Sunscreen (also known as sunblock, suntan lotion) is a lotion, spray or other topical product that is intended to protect the skin from the suns ultraviolet (UV) radiation. ... Sunscreen (also known as sunblock, suntan lotion) is a lotion, spray or other topical product that is intended to protect the skin from the suns ultraviolet (UV) radiation. ... Sunscreen (also known as sunblock, suntan lotion) is a lotion, spray or other topical product that is intended to protect the skin from the suns ultraviolet (UV) radiation. ...

The reddening of the skin due to the action of sunlight depends both on the amount of sunlight as well as the sensitivity of the skin ("erythemal action spectrum") over the UV spectrum.

UVB light can cause direct DNA damage. The radiation excites DNA molecules in skin cells, causing covalent bonds to form between adjacent thymine bases, producing thymidine dimers. Thymidine dimers do not base pair normally, which can cause distortion of the DNA helix, stalled replication, gaps, and misincorporation. These can lead to mutations, which can result in cancerous growths. The mutations that are caused by the direct DNA damage carry a UV signature mutation. The mutagenicity of UV radiation can be easily observed in bacteria cultures. This cancer connection is one reason for concern about ozone depletion and the ozone hole. UVB causes some damage to collagen but at a very much slower rate than UVA. Image File history File links Erythemal_action_spectrum. ... Image File history File links Erythemal_action_spectrum. ... Excitation is the amount of energy (energy in a general sense, not energy as defined in physics) that Curtis has. ... Covalent redirects here. ... For the similarly-spelled vitamin compound, see Thiamine Thymine, also known as 5-methyluracil, is a pyrimidine nucleobase. ... For linguistic mutation, see Apophony. ... Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these to spread, either by direct growth into adjacent tissue through invasion, or by implantation into distant sites by metastasis (where cancer cells are transported through the bloodstream or lymphatic system). ... In biology, a mutagen (Latin, literally origin of change) is a physical or chemical agent that changes the genetic information (usually DNA) of an organism and thus increases the number of mutations above the natural background level. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... Global monthly average total ozone amount Ozone depletion describes two distinct, but related observations: a slow, steady decline of about 4 percent per decade in the total amount of ozone in Earths stratosphere since around 1980; and a much larger, but seasonal, decrease in stratospheric ozone over Earths...

As a defense against UV radiation, the body tans when exposed to moderate (depending on skin type) levels of radiation. UVA gives a quick tan that last for days by oxidizing melanin that was already present and it triggers the release of the melanin from melanocytes. UVB yields a tan that takes roughly 2 days to develop because it stimulates the body to produce more melanin. The purpose of melanin is to block UV-radiation and to dissipate the energy as harmless heat. Thereby the potential damage to the skin tissues is prevented. The photochemical properties of melanin make it an excellent photoprotectant. However, sunscreen chemicals can not dissipate the energy of the excited state as efficiently as melanin and therefore the penetration of sunscreen ingredients into the lower layers of the skin is increasing the amount of free radicals and ROS.^[13] Human skin colour can range from almost black to nearly colorless (appearing pinkish white due to the blood in the skin) in different people. ... Broadly, melanin is any of the polyacetylene, polyaniline, and polypyrrole blacks and browns or their mixed copolymers. ... In chemistry free radicals are uncharged atomic or molecular species with unpaired electrons or an otherwise open shell configuration. ... ROS may refer to: Reparti i Operacioneve Speciale - a special forces unit in Albania Revenue On-Line Service - a tax returns system used in Ireland Review of Systems - a series of medical questions asked to patients regarding the satus of different organ systems Run-of-Schedule (in Television) Run-of...

Sunscreen prevents the direct DNA damage which causes sunburn. Most of these products contain an SPF rating to show how well they block UVB rays. The SPF rating, however, offers no data about UVA protection. In the US, the FDA is considering adding a star rating system to show UVA protection. A similar system is already used in some European countries. Sunscreen (also known as sunblock, suntan lotion) is a lotion, spray or other topical product that is intended to protect the skin from the suns ultraviolet (UV) radiation. ... Sunscreen (also known as sunblock, suntan lotion) is a lotion, spray or other topical product that is intended to protect the skin from the suns ultraviolet (UV) radiation. ... The United States Food and Drug Administration is the government agency responsible for regulating food, dietary supplements, drugs, cosmetics, medical devices, biologics and blood products in the United States. ...

Some sunscreen lotions now include compounds such as titanium dioxide which helps protect against UVA rays. Other UVA blocking compounds found in sunscreen include zinc oxide and avobenzone. Cantaloupe extract, rich in the compound superoxide dismutase (SOD), can be bound with gliadin to form glisodin, an orally-effective protectant against UVB radiation. There are also naturally occurring compounds found in rainforest plants that have been known to protect the skin from UV radiation damage, such as the fern Phlebodium aureum. Flash point non-flammable Related Compounds Other cations Titanium(II) oxide Titanium(III) oxide Titanium(III,IV) oxide Zirconium dioxide Hafnium dioxide Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references Titanium dioxide, also known as titanium... Zinc oxide is a chemical compound with formula ZnO. It is nearly insoluble in water but soluble in acids or alkalis. ... Avobenzone (trade names Parsol® 1789, Eusolex® 9020, Escalol® 517 and others, INCI Butyl Methoxydibenzoylmethane) is an oil soluble ingredient used in sunscreen products to absorb both UVA and UVB rays. ... Trinomial name Cucumis melo cantalupensis Cucumis melo reticulatus Naudin. ... Structure of the monomeric unit of human superoxide dismutase 2 The enzyme superoxide dismutase (SOD, EC 1. ... Gliadin is a glycoprotein, present in wheat and some other cereals, best known for its role, along with glutenin, in the formation of gluten. ... Binomial name Phlebodium aureum (L.) J.Sm. ...

Sunscreen safety debate

The majority of doctors recommend patients protect themselves from UV radiation using sunscreen. Some scientists, however, question the safety of sunscreens that are absorbed into the skin or the bloodstream. These individuals claim these sunscreens generate free radicals under UV-illumination. ^[13] (See the sunscreen controversy article for a full discussion of this issue.)

Eye

High intensities of UVB light are hazardous to the eyes, and exposure can cause welder's flash (photokeratitis or arc eye) and may lead to cataracts, pterygium,^[14][15] and pinguecula formation. Arc eye, also known as arc flash, welders flash, corneal flash burns, or flash burns, is a painful ocular condition sometimes experienced by welders who have failed to use adequate eye protection. ... Arc eye is a painful condition sometimes experienced by welders who have failed to use adequate eye protection. ... Arc eye, also known as arc flash, welders flash, corneal flash burns, or flash burns, is a painful ocular condition sometimes experienced by welders who have failed to use adequate eye protection. ... Human eye cross-sectional view, showing position of human lens. ... A pterygium, meaning wing, is a benign growth of the conjunctiva. ... A Pinguecula is a type of conjunctival degeneration in the eye. ...

Protective eyewear is beneficial to those who are working with or those who might be exposed to ultraviolet radiation, particularly short wave UV. Given that light may reach the eye from the sides, full coverage eye protection is usually warranted if there is an increased risk of exposure, as in high altitude mountaineering. Mountaineers are exposed to higher than ordinary levels of UV radiation, both because there is less atmospheric filtering and because of reflection from snow and ice. Eye protection refers to protective clothing for the eyes, which comes in many types depending upon the threat that is to be reduced. ...

Ordinary, untreated eyeglasses give some protection. Most plastic lenses give more protection than glass lenses, because, as noted above, glass is transparent to UVA and the common acrylic plastic used for lenses is less so. Some plastic lens materials, such as polycarbonate, inherently block most UV. There are protective treatments available for eyeglass lenses that need it which will give better protection. But even a treatment that completely blocks UV will not protect the eye from light that arrives around the lens. Glasses, spectacles, or eyeglasses are frames bearing lenses worn in front of the eyes, sometimes for purely aesthetic reasons but normally for vision correction or eye protection. ... Polycarbonates are a particular group of thermoplastic polyesters. ...

Degradation of polymers, pigments and dyes

Many polymers used in consumer products are degraded by UV light, and need addition of UV absorbers to inhibit attack. The problem appears as discolouration, cracking and sometimes, total product disintegration. A polymer is a long, repeating chain of atoms, formed through the linkage of many molecules called monomers. ...

It is is known as UV degradation, and is one form of polymer degradation. Sensitive polymers include thermoplastics, such as polypropylene and polyethylene as well as speciality fibres like aramids. UV absorption leads to chain degradation and loss of strength. In addition, many pigments and dyes absorb UV and change colour, so paintings and textiles may need extra protection both from sunlight and fluorescent lamps, two common sources of UV radiation. Polymer degradation is a change in the properties - tensile strength, colour, shape, etc - of a polymer or polymer based product under the influence of one or more environmental factors such as heat, light or chemicals. ... Polypropylene lid of a Tic Tacs box, with a living hinge and the resin identification code under its flap Micrograph of polypropylene Polypropylene or polypropene (PP) is a thermoplastic polymer, made by the chemical industry and used in a wide variety of applications, including food packaging, ropes, textiles, stationery, plastic... This article does not cite any references or sources. ... Aramid fiber (1961) is a fire-resistant and strong synthetic fiber. ... In biology, pigment is any material resulting in color in plant or animal cells which is the result of selective absorption. ... A dye can generally be described as a coloured substance that has an affinity to the substrate to which it is being applied. ...

Blockers and absorbers

Ultraviolet Light Absorbers (UVAs) are molecules used in organic materials (polymers, paints, etc.) to absorb UV light in order to reduce the degradation (photo-oxidation) of a material. A number of different UVAs exist with different absorption properties. UVAs can disappear over time, so monitoring of UVA levels in weathered materials is necessary. A polymer is a long, repeating chain of atoms, formed through the linkage of many molecules called monomers. ... For information on the U.S. borough, see Paint, Pennsylvania. ...

In sunscreen, ingredients which absorb UVA/UVB rays, such as avobenzone and octyl methoxycinnamate, are known as absorbers. They are contrasted with physical "blockers" of UV radiation such as titanium dioxide and zinc oxide. (See sunscreen for a more complete list.) Sunscreen (also known as sunblock, suntan lotion) is a lotion, spray or other topical product that is intended to protect the skin from the suns ultraviolet (UV) radiation. ... Flash point non-flammable Related Compounds Other cations Titanium(II) oxide Titanium(III) oxide Titanium(III,IV) oxide Zirconium dioxide Hafnium dioxide Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references Titanium dioxide, also known as titanium... Zinc oxide is a chemical compound with formula ZnO. It is nearly insoluble in water but soluble in acids or alkalis. ... Sunscreen (also known as sunblock, suntan lotion) is a lotion, spray or other topical product that is intended to protect the skin from the suns ultraviolet (UV) radiation. ...

Applications of UV

Security

A bird appears on many Visa credit cards when held under a UV light source.

To help thwart counterfeiters, sensitive documents (e.g. credit cards, driver's licenses, passports) may also include a UV watermark that can only be seen when viewed under a UV-emitting light. Passports issued by most countries usually contain UV sensitive inks and security threads. Visa stamps and stickers on passports of visitors contain large and detailed seals invisible to the naked eye under normal lights, but strongly visible under UV illumination. Passports issued by many nations have UV sensitive watermarks on all pages of the passport. Currencies of various countries' banknotes have an image, as well as many multicolored fibers, that are visible only under ultraviolet light. A counterfeit is an imitation that is made with the intent to deceptively represent its content or origins. ... This article is about the payment system. ... First German driving school in 1906, Aschaffenburg Current EU driving licence, German version - front 1. ... For Microsoft Corporation’s “universal login” service, formerly known as Microsoft Passport Network, see Windows Live ID. For other types of travel document, see Travel document. ... Entry visa valid in Schengen treaty countries. ... The naked eye is a figure of speech referring to human visual perception that is unaided by enhancing equipment, such as a telescope or binoculars. ... Canadian banknotes are the banknotes of Canada, denominated in Canadian dollars (CAD). ...

Fluorescent lamps

Fluorescent lamps produce UV radiation by ionising low-pressure mercury vapour. A phosphorescent coating on the inside of the tubes absorbs the UV and converts it to visible light. Fluorescent lamps Assorted types of fluorescent lamps. ... This article is about the element. ...

The main mercury emission wavelength is in the UVC range. Unshielded exposure of the skin or eyes to mercury arc lamps that do not have a conversion phosphor is quite dangerous.

The light from a mercury lamp is predominantly at discrete wavelengths. Other practical UV sources with more continuous emission spectra include xenon arc lamps (commonly used as sunlight simulators), deuterium arc lamps, mercury-xenon arc lamps, metal-halide arc lamps, and tungsten-halogen incandescent lamps. Xenon flash lamp being fired. ...

Astronomy

Aurora at Jupiter's north pole as seen in ultraviolet light by the Hubble Space Telescope.

In astronomy, very hot objects preferentially emit UV radiation (see Wien's law). Because the ozone layer blocks many UV frequencies from reaching telescopes on the surface of the Earth, most UV observations are made from space. (See UV astronomy, space observatory.) Image File history File links Download high resolution version (2842x1617, 503 KB)Satellite Footprints Seen in Jupiter Aurora. ... Image File history File links Download high resolution version (2842x1617, 503 KB)Satellite Footprints Seen in Jupiter Aurora. ... Aurora borealis Aurora borealis The aurora is a glow observed in the night sky, usually in the polar zone. ... For other uses, see Jupiter (disambiguation). ... For other uses, see Astronomy (disambiguation). ... Wiens displacement law is a law of physics that states that there is an inverse relationship between the wavelength of the peak of the emission of a black body and its temperature. ... UV astronomy is the branch of astronomy and astrophysics which deals with objects visible in ultraviolet (UV) radiation. ... Space telescopes A space observatory is any instrument in outer space which is used for observation of distant planets, galaxies, and other outer space objects. ...

Biological surveys and pest control

Some animals, including birds, reptiles, and insects such as bees, can see into the near ultraviolet. Many fruits, flowers, and seeds stand out more strongly from the background in ultraviolet wavelengths as compared to human color vision. Scorpions glow or take on a yellow to green color under UV illumination. Many birds have patterns in their plumage that are invisible at usual wavelengths but observable in ultraviolet, and the urine and other secretions of some animals, including dogs, cats, and human beings, is much easier to spot with ultraviolet. For other uses, see Bird (disambiguation). ... Reptilia redirects here. ... Orders Subclass Apterygota Archaeognatha (bristletails) Thysanura (silverfish) Subclass Pterygota Infraclass Paleoptera (Probably paraphyletic) Ephemeroptera (mayflies) Odonata (dragonflies and damselflies) Infraclass Neoptera Superorder Exopterygota Grylloblattodea (ice-crawlers) Mantophasmatodea (gladiators) Plecoptera (stoneflies) Embioptera (webspinners) Zoraptera (angel insects) Dermaptera (earwigs) Orthoptera (grasshoppers, etc) Phasmatodea (stick insects) Blattodea (cockroaches) Isoptera (termites) Mantodea (mantids) Psocoptera... For other uses, see Western honey bee and Bee (disambiguation). ... Superfamilies Pseudochactoidea Buthoidea Chaeriloidea Chactoidea Iuroidea Scorpionoidea See classification for families. ...

Many insects use the ultraviolet wavelength emissions from celestial objects as references for flight navigation. A local ultraviolet emissor will normally disrupt the navigation process and would eventually attract to itself the flying insect.

Entomologist using a UV light for collecting beetles in the Paraguayan Chaco.

Ultraviolet traps are used to eliminate various small flying insects. They are attracted to the UV light, and are killed using an electric shock, or trapped once they come into contact with the device. Different designs of ultraviolet light traps are also used by entomologists for collecting nocturnal insects during faunistic survey studies. For other uses, see Beetle (disambiguation). ... There are things that have the name Chaco: South America: Gran Chaco, a region in South America Chaco Province, Argentina in the northeastern part of the country Chaco, a region in Paraguay Chaco Department, historical in Paraguay and proposed in Bolivia Gran Chaco Province, Bolivia (in Tarija Department) Chaco War... Entomology is the scientific study of insects. ... In Christian liturgy, a collect is both a liturgical action and a short, general prayer. ... A nocturnal animal is one that sleeps during the day and is active at night - the opposite of the human (diurnal) schedule. ...

Spectrophotometry

UV/VIS spectroscopy is widely used as a technique in chemistry, to analyze chemical structure, most notably conjugated systems. UV radiation is often used in visible spectrophotometry to determine the existence of fluorescence in a given sample. Ultraviolet-Visible Spectroscopy or Ultraviolet-Visible Spectrophotometry (UV/ VIS) involves the spectroscopy of photons (spectrophotometry). ... For other uses, see Chemistry (disambiguation). ... Chemical structure refers to the spatial arrangement of atoms in a molecule and the chemical bonds that hold the atoms together. ... A chemically conjugated system, is a system of atoms covalently bonded with alternating single and double bonds (e. ... Spectrophotometer In physics, spectrophotometry is the quantitative study of electromagnetic spectra. ...

Analyzing minerals

A collection of mineral samples brilliantly fluorescing at various wavelengths as seen while being irradiated by UV light.

Ultraviolet lamps are also used in analyzing minerals, gems, and in other detective work including authentication of various collectibles. Materials may look the same under visible light, but fluoresce to different degrees under ultraviolet light; or may fluoresce differently under short wave ultraviolet versus long wave ultraviolet. Image File history File linksMetadata Download high resolution version (2560x1650, 532 KB) Summary Description: Collection of various fluorescent minerals under UV-A, UV-B and UV-C light Source: made by author Date: April 2005 Author: Hannes Grobe Permission: {{{Permission}}} Licensing File links The following pages link to this file... Image File history File linksMetadata Download high resolution version (2560x1650, 532 KB) Summary Description: Collection of various fluorescent minerals under UV-A, UV-B and UV-C light Source: made by author Date: April 2005 Author: Hannes Grobe Permission: {{{Permission}}} Licensing File links The following pages link to this file... For other uses, see Mineral (disambiguation). ... Minerals are natural compounds formed through geological processes. ... For other uses, see Gemstone (disambiguation). ... A collectible (or collectable) is typically a manufactured item designed for people to collect. ... Fluorescence induced by exposure to ultraviolet light in vials containing various sized Cadmium selenide (CdSe) quantum dots. ...

Chemical markers

UV fluorescent dyes are used in many applications (for example, biochemistry and forensics). The Green Fluorescent Protein (GFP) is often used in genetics as a marker. Many substances, such as proteins, have significant light absorption bands in the ultraviolet that are of use and interest in biochemistry and related fields. UV-capable spectrophotometers are common in such laboratories. Look up dye in Wiktionary, the free dictionary. ... Wöhler observes the synthesis of urea. ... Forensics redirects here. ... It has been suggested that mGFP be merged into this article or section. ... This article is about the general scientific term. ...

Photochemotherapy

Exposure to UVA light while the skin is hyper-photosensitive by taking psoralens is an effective treatment for psoriasis called PUVA. Due to psoralens potentially causing damage to the liver, PUVA may only be used a limited number of times over a patient's lifetime. Psoralen (also called psoralene) is the parent compound in a family of natural products known as furocoumarins. ... PUVA is a Psoralen + UVA treatment. ... Psoralen (also called psoralene) is the parent compound in a family of natural products known as furocoumarins. ... The liver is the largest internal organ in the human body, and is an organ present in vertebrates and some other animals. ... PUVA is a Psoralen + UVA treatment. ...

Phototherapy

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Exposure to UVB light, particularly the 310 nm narrowband UVB range, is an effective long-term treatment for many skin conditions like psoriasis, vitiligo, eczema, and many others. UVB phototherapy does not require additional medications or topical preparations for the therapeutic benefit; only the light exposure is needed. However, phototherapy can be effective when used in conjunction with certain topical treatments such as anthralin, coal tar, and Vitamin A and D derivatives, or systemic treatments such as methotrexate and soriatane.^[16] Not to be confused with alphos, a form of leprosy once called vitiligo. ... For the beetle, see Exema. ...

Typical treatment regimes involve short exposure to UVB rays 3 to 5 times a week at a hospital or clinic, and for the best results, up to 30 or more sessions may be required.

Side effects may include itching and redness of the skin due to UVB exposure, and possibly sunburn, if patients do not minimize exposure to natural UV rays during treatment days.

Photolithography

Ultraviolet radiation is used for very fine resolution photolithography, a procedure where a chemical known as a photoresist is exposed to UV radiation which has passed through a mask. The light allows chemical reactions to take place in the photoresist, and after development (a step that either removes the exposed or unexposed photoresist), a geometric pattern which is determined by the mask remains on the sample. Further steps may then be taken to "etch" away parts of the sample with no photoresist remaining. Photolithography is a process used in semiconductor device fabrication to transfer a pattern from a photomask (also called reticle) to the surface of a substrate. ...

UV radiation is used extensively in the electronics industry because photolithography is used in the manufacture of semiconductors, integrated circuit components^[17] and printed circuit boards. A semiconductor is a solid material that has electrical conductivity in between that of a conductor and that of an insulator; it can vary over that wide range either permanently or dynamically. ... Integrated circuit of Atmel Diopsis 740 System on Chip showing memory blocks, logic and input/output pads around the periphery Microchips with a transparent window, showing the integrated circuit inside. ... Part of a 1983 Sinclair ZX Spectrum computer board. ...

Checking electrical insulation

A new application of UV is to detect corona discharge (often simply called "corona") on electrical apparatus. Degradation of insulation of electrical apparatus or pollution causes corona, wherein a strong electric field ionizes the air and excites nitrogen molecules, causing the emission of ultraviolet radiation. The corona degrades the insulation level of the apparatus. Corona produces ozone and to a lesser extent nitrogen oxide which may subsequently react with water in the air to form nitrous acid and nitric acid vapour in the surrounding air.^[18] In electricity, a corona discharge is an electrical discharge brought on by the ionization of a fluid surrounding a conductor, which occurs when the potential gradient exceeds a certain value, in situations where sparking (also known as arcing) is not favoured. ... For other uses, see Ozone (disambiguation). ... // The term nitrogen oxide typically refers to any binary compound of oxygen and nitrogen, or to a mixture of such compounds: Nitric oxide (NO), nitrogen(II) oxide Nitrogen dioxide (NO2), nitrogen(IV) oxide Nitrous oxide (N2O), nitrogen (I) oxide Dinitrogen trioxide (N2O3), nitrogen(II, IV) oxide Dinitrogen tetroxide (N2O4), nitrogen... Nitrous acid (molecular formula HNO2) is a weak monobasic acid known only in solution and in the form of nitrite salts. ... The chemical compound nitric acid (HNO3), also known as aqua fortis and spirit of nitre, is an aqueous solution of hydrogen nitrate (anhydrous nitric acid). ...

Sterilization

Main article: Ultraviolet germicidal irradiation

A low pressure mercury vapor discharge tube floods the inside of a hood with shortwave UV light when not in use, sterilizing microbiological contaminants from irradiated surfaces.

Ultraviolet lamps are used to sterilize workspaces and tools used in biology laboratories and medical facilities. Commercially-available low pressure mercury-vapor lamps emit about 86% of their light at 254 nanometers (nm) which coincides very well with one of the two peaks of the germicidal effectiveness curve (i.e., effectiveness for UV absorption by DNA). One of these peaks is at about 265 nm and the other is at about 185 nm. Although 185 nm is better absorbed by DNA, the quartz glass used in commercially-available lamps, as well as environmental media such as water, are more opaque to 185 nm than 254 nm (C. von Sonntag et al., 1992). UV light at these germicidal wavelengths causes adjacent thymine molecules on DNA to dimerize, if enough of these defects accumulate on a microorganism's DNA its replication is inhibited, thereby rendering it harmless (even though the organism may not be killed outright). However, since microorganisms can be shielded from ultraviolet light in small cracks and other shaded areas, these lamps are used only as a supplement to other sterilization techniques. A low pressure mercury vapor discharge tube floods the inside of a hood with shortwave UV light when not in use, sterilizing microbiological contaminants from irradiated surfaces. ... Image File history File linksMetadata Download high resolution version (2560x1920, 2401 KB) Summary UV light decontaminates the laminar flow bench when not used Licensing File links The following pages link to this file: Ultraviolet Metadata This file contains additional information, probably added from the digital camera or scanner used to... Image File history File linksMetadata Download high resolution version (2560x1920, 2401 KB) Summary UV light decontaminates the laminar flow bench when not used Licensing File links The following pages link to this file: Ultraviolet Metadata This file contains additional information, probably added from the digital camera or scanner used to... A common modern fume hood. ... Sterilization (or sterilisation) refers to any process that effectively kills or eliminates transmissible agents (such as fungi, bacteria, viruses and prions) from a surface, equipment, foods, medications, or biological culture medium. ... Visible spectrum of a mercury-vapor lamp A Mercury-vapor lamp is a gas discharge lamp which uses mercury in an excited state to produce light. ... Fused quartz is a man-made material manufactured principally from sands. ... For the similarly-spelled vitamin compound, see Thiamine Thymine, also known as 5-methyluracil, is a pyrimidine nucleobase. ... Sucrose, or common table sugar, is composed of glucose and fructose. ...

Disinfecting drinking water

UV radiation can be an effective viricide and bactericide. Disinfection using UV radiation is commonly used in wastewater treatment applications and is finding an increased usage in drinking water treatment. Many bottlers of spring water use UV disinfection equipment to sterilize their water. Solar water disinfection is the process of using PET bottles and sunlight to disinfect water. A viricide is a chemical agent which kills viruses outside the body. ... A bacteriocide or bactericide is a substance that kills bacteria and, preferably, nothing else. ... This article or section is in need of attention from an expert on the subject. ... This article is about animals kept for companionship. ...

New York City has approved the construction of a 2 billion gallon per day ultraviolet drinking water disinfection facility^[19]. There are also several facilities under construction and several in operation that treat waste water with several stages of filters