1.
Bioluminescence
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Bioluminescence is the production and emission of light by a living organism. It is a form of chemiluminescence, Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some bioluminescent bacteria and terrestrial invertebrates such as fireflies. In some animals, the light is produced by organisms such as Vibrio bacteria. The principal chemical reaction in bioluminescence involves the light-emitting pigment luciferin, the enzyme catalyzes the oxidation of luciferin. In some species, the type of luciferin requires cofactors such as calcium or magnesium ions, in evolution, luciferins vary little, one in particular, coelenterazine, is found in nine different animal, though in some of these, the animals obtain it through their diet. Conversely, luciferases vary widely in different species, Bioluminescence has arisen over forty times in evolutionary history. It was not until the nineteenth century that bioluminescence was properly investigated. The phenomenon is widely distributed among animal groups, especially in environments where dinoflagellates cause phosphorescence in the surface layers of water. On land it occurs in fungi, bacteria and some groups of invertebrates, in the laboratory, luciferase-based systems are used in genetic engineering and for biomedical research. Other researchers are investigating the possibility of using bioluminescent systems for street and decorative lighting, before the development of the safety lamp for use in coal mines, dried fish skins were used in Britain and Europe as a weak source of light. This experimental form of illumination avoided the necessity of using candles which risked sparking explosions of firedamp, another safe source of illumination in mines was bottles containing fireflies. In 1920, the American zoologist E. Newton Harvey published a monograph, The Nature of Animal Light, Harvey notes that Aristotle mentions light produced by dead fish and flesh, and that both Aristotle and Pliny the Elder mention light from damp wood. He also records that Robert Boyle experimented on these light sources, tuckey, in his posthumous 1818 Narrative of the Expedition to the Zaire, described catching the animals responsible for luminescence. He mentions pellucids, crustaceans, and cancers, under the microscope he described the luminous property to be in the brain, resembling a most brilliant amethyst about the size of a large pins head. Charles Darwin noticed bioluminescence in the sea, describing it in his Journal, While sailing in these latitudes on one very dark night, the sea presented a wonderful and most beautiful spectacle. There was a breeze, and every part of the surface. The vessel drove before her bows two billows of liquid phosphorus, and in her wake she was followed by a milky train. Darwin also observed a luminous jelly-fish of the genus Dianaea and noted that When the waves scintillate with bright green sparks, but there can be no doubt that very many other pelagic animals, when alive, are phosphorescent
2.
Europium
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Europium is a chemical element with symbol Eu and atomic number 63. It was isolated in 1901 and is named after the continent of Europe and it is a moderately hard, silvery metal which readily oxidizes in air and water. Being a typical member of the series, europium usually assumes the oxidation state +3. All europium compounds with oxidation state +2 are slightly reducing, Europium has no significant biological role and is relatively non-toxic compared to other heavy metals. Most applications of europium exploit the phosphorescence of europium compounds, Europium is one of the least abundant elements in the universe, only about 5×10−8% of all matter in the universe is europium. Europium is a metal with a hardness similar to that of lead. It crystallizes in a cubic lattice. Some properties of europium are strongly influenced by its half-filled electron shell, Europium has the second lowest melting point and the lowest density of all lanthanides. Europium becomes a superconductor when it is cooled below 1.8 K and this is because europium is divalent in the metallic state, and is converted into the trivalent state by the applied pressure. In the divalent state, the local magnetic moment suppresses the superconductivity. Europium is the most reactive rare earth element and it rapidly oxidizes in air, so that bulk oxidation of a centimeter-sized sample occurs within several days. This behavior is unusual to most lanthanides, which almost exclusively form compounds with a state of +3. The +2 state has an electron configuration 4f7 because the half-filled f-shell gives more stability, in terms of size and coordination number, europium and barium are similar. For example, the sulfates of both barium and europium are also highly insoluble in water, divalent europium is a mild reducing agent, oxidizing in air to form Eu compounds. In anaerobic, and particularly geothermal conditions, the divalent form is sufficiently stable that it tends to be incorporated into minerals of calcium and the other alkaline earths. This ion-exchange process is the basis of the europium anomaly. Bastnäsite tends to show less of a negative europium anomaly than does monazite, the development of easy methods to separate divalent europium from the other lanthanides made europium accessible even when present in low concentration, as it usually is. Naturally occurring europium is composed of 2 isotopes, 151Eu and 153Eu, while 153Eu is stable, 151Eu was recently found to be unstable to alpha decay with half-life of 5+11 −3×1018 years, giving about 1 alpha decay per two minutes in every kilogram of natural europium
3.
Strontium
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Strontium is a chemical element with symbol Sr and atomic number 38. An alkaline earth metal, strontium is a soft silver-white or yellowish metallic element that is highly reactive chemically, the metal forms a dark oxide layer when it is exposed to air. Strontium has physical and chemical properties similar to those of its two neighbors in the periodic table, calcium and barium. It occurs naturally in the minerals celestine, strontianite, and putnisite, natural stable strontium, on the other hand, is not hazardous to health. Strontium was first isolated as a metal in 1808 by Humphry Davy using the then-newly discovered process of electrolysis, the production of sugar from sugar beet was in the 19th century the largest application of strontium. At the peak of production of cathode ray tubes, as much as 75 percent of strontium consumption in the United States was used for the faceplate glass. With the displacement of cathode ray tubes by other display methods, Strontium is a divalent silvery metal with a pale yellow tint whose properties are mostly intermediate between and similar to those of its group neighbors calcium and barium. It is softer than calcium and harder than barium and its melting and boiling points are lower than those of calcium, barium continues this downward trend in the melting point, but not in the boiling point. The density of strontium is similarly intermediate between those of calcium and barium, three allotropes of metallic strontium exist, with transition points at 235 and 540 °C. The standard electrode potential for the Sr2+/Sr couple is −2.89 V, Strontium is intermediate between calcium and barium in its reactivity toward water, with which it reacts on contact to produce strontium hydroxide and hydrogen gas. Strontium metal burns in air to produce both strontium oxide and strontium nitride, but since it does not react with nitrogen below 380 °C, at room temperature, it forms only the oxide spontaneously. Besides the simple oxide SrO, the peroxide SrO2 can be made by oxidation of strontium metal under a high pressure of oxygen. Strontium hydroxide, Sr2, is a base, though it is not as strong as the hydroxides of barium or the alkali metals. Due to the size of the heavy s-block elements, including strontium. Organostrontium compounds contain one or more strontium–carbon bonds and they have been reported as intermediates in Barbier-type reactions. Organostrontium compounds tend to be similar to organoeuropium or organosamarium compounds due to the similar ionic radii of these elements. Most of these compounds can only be prepared at low temperatures, because of its extreme reactivity with oxygen and water, this element occurs naturally only in compounds with other elements, such as in the minerals strontianite and celestine. It is kept under a liquid such as mineral oil or kerosene to prevent oxidation
4.
Ultraviolet
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Ultraviolet is an electromagnetic radiation with a wavelength from 10 nm to 400 nm, shorter than that of visible light but longer than X-rays. UV radiation constitutes about 10% of the light output of the Sun. It is also produced by electric arcs and specialized lights, such as lamps, tanning lamps. Consequently, the effects of UV are greater than simple heating effects. Suntan, freckling and sunburn are familiar effects of over-exposure, along with risk of skin cancer. Living things on dry land would be damaged by ultraviolet radiation from the Sun if most of it were not filtered out by the Earths atmosphere. More-energetic, shorter-wavelength extreme UV below 121 nm ionizes air so strongly that it is absorbed before it reaches the ground, Ultraviolet is also responsible for the formation of bone-strengthening vitamin D in most land vertebrates, including humans. The UV spectrum thus has both beneficial and harmful to human health. Ultraviolet rays are invisible to most humans, the lens in a human eye ordinarily filters out UVB frequencies or higher, and humans lack color receptor adaptations for ultraviolet rays. Under some conditions, children and young adults can see ultraviolet down to wavelengths of about 310 nm, near-UV radiation is visible to some insects, mammals, and birds. Small birds have a fourth color receptor for ultraviolet rays, this gives birds true UV vision, reindeer use near-UV radiation to see polar bears, who are poorly visible in regular light because they blend in with the snow. UV also allows mammals to see urine trails, which is helpful for animals to find food in the wild. The males and females of some species look identical to the human eye. Ultraviolet means beyond violet, violet being the color of the highest frequencies of visible light, Ultraviolet has a higher frequency than violet light. He called them oxidizing rays to emphasize chemical reactivity and to them from heat rays. The terms chemical and heat rays were eventually dropped in favour of ultraviolet and infrared radiation, in 1878 the effect of short-wavelength light on sterilizing bacteria was discovered. By 1903 it was known the most effective wavelengths were around 250 nm, in 1960, the effect of ultraviolet radiation on DNA was established. The discovery of the ultraviolet radiation below 200 nm, named vacuum ultraviolet because it is absorbed by air, was made in 1893 by the German physicist Victor Schumann
5.
Fluorescence
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Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence, in most cases, the emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation. Fluorescent materials cease to glow immediately when the radiation source stops, unlike phosphorescence, Fluorescence also occurs frequently in nature in some minerals and in various biological states in many branches of the animal kingdom. An early observation of fluorescence was described in 1560 by Bernardino de Sahagún and it was derived from the wood of two tree species, Pterocarpus indicus and Eysenhardtia polystachya. The chemical compound responsible for this fluorescence is matlaline, which is the product of one of the flavonoids found in this wood. The name was derived from the fluorite, some examples of which contain traces of divalent europium. In a key experiment he used a prism to isolate ultraviolet radiation from sunlight, the specific frequencies of exciting and emitted light are dependent on the particular system. S0 is called the state of the fluorophore, and S1 is its first excited singlet state. A molecule in S1 can relax by various competing pathways and it can undergo non-radiative relaxation in which the excitation energy is dissipated as heat to the solvent. Excited organic molecules can also relax via conversion to a triplet state, relaxation from S1 can also occur through interaction with a second molecule through fluorescence quenching. Molecular oxygen is an extremely efficient quencher of fluorescence just because of its unusual triplet ground state, in most cases, the emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation, this phenomenon is known as the Stokes shift. The emitted radiation may also be of the wavelength as the absorbed radiation. Molecules that are excited through light absorption or via a different process can transfer energy to a second sensitized molecule, the fluorescence quantum yield gives the efficiency of the fluorescence process. It is defined as the ratio of the number of photons emitted to the number of photons absorbed, Φ = Number of photons emitted Number of photons absorbed The maximum fluorescence quantum yield is 1.0, each photon absorbed results in a photon emitted. Compounds with quantum yields of 0.10 are still considered quite fluorescent, thus, if the rate of any pathway changes, both the excited state lifetime and the fluorescence quantum yield will be affected. Fluorescence quantum yields are measured by comparison to a standard, the quinine salt quinine sulfate in a sulfuric acid solution is a common fluorescence standard. The fluorescence lifetime refers to the time the molecule stays in its excited state before emitting a photon. This is an instance of exponential decay, various radiative and non-radiative processes can de-populate the excited state
6.
Flashtube
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A flashtube, also called a flashlamp, is an electric arc lamp designed to produce extremely intense, incoherent, full-spectrum white light for very short durations. Flashtubes are made of a length of tubing with electrodes at either end and are filled with a gas that. Flashtubes are used mostly for photographic purposes but are employed in scientific, medical, industrial. The lamp comprises a hermetically sealed tube, which is filled with a noble gas, usually xenon. Additionally, a high power source is necessary to energize the gas as a trigger event. A charged capacitor is used to supply energy for the flash. In some applications, the emission of light is undesired, whether due to production of ozone, damage to laser rods, degradation of plastics. In these cases, a fused silica is used. A better alternative is a cerium-doped quartz, it does not suffer from solarization and has higher efficiency and its cutoff is at about 380 nm. The power level of the lamps is rated in watts/area, total electrical input power divided by the inner wall surface. Cooling of the electrodes and the envelope is of high importance at high power levels. Air cooling is sufficient for lower power levels. High power lamps are cooled with a liquid, typically by flowing demineralized water through a tube in which the lamp is encased, water-cooled lamps will generally have the glass shrunk around the electrodes, to provide a direct thermal conductor between them and the cooling water. The cooling medium should flow also across the length of the lamp. Above 15 W/cm2 forced air cooling is required, liquid cooling if in a confined space, liquid cooling is generally necessary above 30 W/cm2. For this reason, thinner glass is used for continuous-wave arc-lamps. Thicker materials can generally handle more impact energy from the wave that a short-pulsed arc can generate. The material of the envelope provides another limit for the power,1 mm thick fused quartz has a limit of 200 W/cm2
7.
Fused quartz
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Fused quartz or fused silica is glass consisting of silica in amorphous form. It differs from traditional glasses in containing no other ingredients, which are added to glass to lower the melt temperature. Fused silica, therefore, has high working and melting temperatures, the optical and thermal properties of fused quartz are superior to those of other types of glass due to its purity. For these reasons, it use in situations such as semiconductor fabrication. It has better ultraviolet transmission than most other glasses, and so is used to make lenses and its low coefficient of thermal expansion also makes it a useful material for precision mirror substrates. Fused quartz is produced by fusing high-purity silica sand, which consists of quartz crystals, quartz contains only silicon and oxygen, although commercial quartz glass often contains impurities. The most dominant impurities are aluminium and titanium, melting is effected at approximately 1650 °C using either an electrically heated furnace or a gas/oxygen-fuelled furnace. This results in a transparent glass with a purity and improved optical transmission in the deep ultraviolet. Fused quartz is normally transparent, the process of fusion results in a material that is translucent, the material can however appear opaque owing to the presence of small air bubbles trapped within the material. The water content is determined by the manufacturing process, flame fused material always has a higher water content due to the combination of the hydrocarbons and oxygen fuelling the furnace forming hydroxyl groups within the material. An IR grade material typically has an content of <10 parts per million, most of the applications of fused silica exploit its wide transparency range, which extends from the UV to the near IR. Fused silica is the key starting material for optical fiber, used for telecommunications, vacuum tubes with silica envelopes allowed for radiation cooling by incandescent anodes. Because of its strength fused silica was used in deep diving vessels such as the Bathysphere, the combination of strength, thermal stability, and UV transparency makes it an excellent substrate for projection masks for photolithography. EPROMs are recognizable by the transparent fused quartz window which sits on top of the package, through which the chip is visible. Due to the stability and composition it is used in semiconductor fabrication furnaces. Fused quartz has nearly ideal properties for fabricating first surface mirrors such as used in telescopes. The material behaves in a way and allows the optical fabricator to put a very smooth polish onto the surface and produce the desired figure with fewer testing iterations. These lenses are used for UV photography, as the glass has a lower extinction rate than lens made with more common flint or crown glass formulas
8.
Luminous paint
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Luminous paint or luminescent paint is paint that exhibits luminescence. In other words, it gives off light through fluorescence, phosphorescence. Fluorescent paints offer a range of pigments and chroma which also glow when exposed to the long-wave ultraviolet frequencies. These UV frequencies are found in sunlight and some artificial lights, human eyes perceive these changes as the unusual glow of fluorescence. The fluorescent type of luminescence is different from the natural bio-luminescence of bacteria, insects and fish such as the case of the firefly. Bio-luminescence involves no reflection at all, but living generation of light, there are both visible and invisible fluorescent paints. The visible appear under white light to be any bright color, invisible fluorescent paints appear transparent or pale under daytime lighting, but will glow under UV light in a limited range of colors. Since these can seem to disappear, they can be used to create a variety of clever effects, both types of fluorescent painting benefit when used within a contrasting ambiance of clean, matte-black backgrounds and borders. Such a black out effect will minimize other awareness, so cultivating the peculiar luminescence of UV fluorescence, both types of paints have extensive application where artistic lighting effects are desired, particularly in black box entertainments and environments such as theaters, bars, shrines, etc. Out-of-doors, however, UV wavelengths are scattered in space or absorbed by complex natural surfaces. Furthermore, the complex pigments will degrade quickly in sunlight, phosphorescent paint is commonly called glow-in-the-dark paint. It is made from such as silver-activated zinc sulfide or doped strontium aluminate. The mechanism for producing light is similar to that of fluorescent paint, phosphorescent paints have a sustained glow which lasts for up to 12 hours after exposure to light, fading over time. This type of paint has been used to mark escape paths in aircraft and for use such as stars applied to walls. It is an alternative to radioluminescent paint, kenners Lightning Bug Glo-Juice was a popular non-toxic paint product in 1968, marketed at children, alongside other glow-in-the-dark toys and novelties. When applied as a paint or a more sophisticated coating, phosphorescence can be used for detection or degradation measurements known as phosphor thermometry. Radioluminescent paint contains a radioactive isotope combined with a radioluminescent substance, the isotopes selected are typically strong emitters of fast electrons, preferred since this radiation will not penetrate an enclosure. Radioluminescent paints will glow without exposure to light until the radioactive isotope has decayed and they are therefore sometimes referred to as self-luminous
9.
National Diet Library
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The National Diet Library is the only national library in Japan. It was established in 1948 for the purpose of assisting members of the National Diet of Japan in researching matters of public policy, the library is similar in purpose and scope to the United States Library of Congress. The National Diet Library consists of two facilities in Tokyo and Kyoto, and several other branch libraries throughout Japan. The Diets power in prewar Japan was limited, and its need for information was correspondingly small, the original Diet libraries never developed either the collections or the services which might have made them vital adjuncts of genuinely responsible legislative activity. Until Japans defeat, moreover, the executive had controlled all political documents, depriving the people and the Diet of access to vital information. The U. S. occupation forces under General Douglas MacArthur deemed reform of the Diet library system to be an important part of the democratization of Japan after its defeat in World War II. In 1946, each house of the Diet formed its own National Diet Library Standing Committee, hani Gorō, a Marxist historian who had been imprisoned during the war for thought crimes and had been elected to the House of Councillors after the war, spearheaded the reform efforts. Hani envisioned the new body as both a citadel of popular sovereignty, and the means of realizing a peaceful revolution, the National Diet Library opened in June 1948 in the present-day State Guest-House with an initial collection of 100,000 volumes. The first Librarian of the Diet Library was the politician Tokujirō Kanamori, the philosopher Masakazu Nakai served as the first Vice Librarian. In 1949, the NDL merged with the National Library and became the national library in Japan. At this time the collection gained a million volumes previously housed in the former National Library in Ueno. In 1961, the NDL opened at its present location in Nagatachō, in 1986, the NDLs Annex was completed to accommodate a combined total of 12 million books and periodicals. The Kansai-kan, which opened in October 2002 in the Kansai Science City, has a collection of 6 million items, in May 2002, the NDL opened a new branch, the International Library of Childrens Literature, in the former building of the Imperial Library in Ueno. This branch contains some 400,000 items of literature from around the world. Though the NDLs original mandate was to be a library for the National Diet. In the fiscal year ending March 2004, for example, the library reported more than 250,000 reference inquiries, in contrast, as Japans national library, the NDL collects copies of all publications published in Japan. The NDL has an extensive collection of some 30 million pages of documents relating to the Occupation of Japan after World War II. This collection include the documents prepared by General Headquarters and the Supreme Commander of the Allied Powers, the Far Eastern Commission, the NDL maintains a collection of some 530,000 books and booklets and 2 million microform titles relating to the sciences
10.
Radioactive decay
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A material containing such unstable nuclei is considered radioactive. Certain highly excited short-lived nuclear states can decay through neutron emission, or more rarely, however, for a collection of atoms, the collections expected decay rate is characterized in terms of their measured decay constants or half-lives. This is the basis of radiometric dating, the half-lives of radioactive atoms have no known upper limit, spanning a time range of over 55 orders of magnitude, from nearly instantaneous to far longer than the age of the universe. A radioactive nucleus with spin can have no defined orientation. If there are multiple particles produced during a single decay, as in decay, their relative angular distribution. Such a parent process could be a previous decay, or a nuclear reaction, the decaying nucleus is called the parent radionuclide, and the process produces at least one daughter nuclide. Except for gamma decay or internal conversion from an excited state. When the number of changes, an atom of a different chemical element is created. The first decay processes to be discovered were alpha decay, beta decay, alpha decay occurs when the nucleus ejects an alpha particle. This is the most common process of emitting nucleons, but highly excited nuclei can eject single nucleons, or in the case of cluster decay, specific light nuclei of other elements. Beta decay occurs when the nucleus emits an electron or positron, the nucleus may capture an orbiting electron, causing a proton to convert into a neutron in a process called electron capture. All of these result in a well-defined nuclear transmutation. By contrast, there are radioactive decay processes that do not result in a nuclear transmutation, another type of radioactive decay results in products that vary, appearing as two or more fragments of the original nucleus with a range of possible masses. For a summary table showing the number of stable and radioactive nuclides in each category, there are 29 naturally occurring chemical elements on Earth that are radioactive. They are those that contain 34 radionuclides that date before the time of formation of the solar system, well-known examples are uranium and thorium, but also included are naturally occurring long-lived radioisotopes, such as potassium-40. Radioactivity was discovered in 1896 by the French scientist Henri Becquerel and these materials glow in the dark after exposure to light, and he suspected that the glow produced in cathode ray tubes by X-rays might be associated with phosphorescence. He wrapped a photographic plate in black paper and placed various phosphorescent salts on it, all results were negative until he used uranium salts. The uranium salts caused a blackening of the plate in spite of the plate being wrapped in black paper and these radiations were given the name Becquerel Rays
11.
Glow stick
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A glow stick is a self-contained, short-term light-source. It consists of a translucent plastic tube containing isolated substances that, the light cannot be turned off and can only be used once. Glow sticks are used for recreation, but may also be relied upon for light during military, police, fire. Bisoxalate, trademarked Cyalume, was invented by Michael M. Rauhut and Laszlo J. Bollyky of American Cyanamid, other early work on chemiluminescence was carried out at the same time, by researchers under Herbert Richter at China Lake Naval Weapons Center. Several US patents for glow stick type devices were received by various inventors, bernard Dubrow and Eugene Daniel Guth patented a Packaged Chemiluminescent Material in June 1965. In October 1973, Clarence W. Gilliam, David Iba Sr. in June 1974 a patent for a Chemiluminescent Device was issued with Herbert P. Richter and Ruth E. Tedrick listed as the inventors. In January 1976, a patent was issued for the Chemiluminescent Signal Device, with Vincent J. Esposito, Steven M. Little and this patent recommended a single glass ampoule that is suspended in a second substance, that when broken and mixed together, provide the chemiluminescent light. The design also included a stand for the device so it could be thrown from a moving vehicle. In December 1977 a patent was issued for a Chemical Light Device with Richard Taylor Van Zandt as the inventor, glow sticks are waterproof, do not use batteries, generate negligible heat, are inexpensive, and are reasonably disposable. They can tolerate high pressures, such as found under water. They are used as sources and light markers by military forces, campers. Glow sticks are considered the light source that is safe for use immediately following any catastrophic event. Glowsticking is the use of sticks in dancing. This is one of their most widely known uses in popular culture, as they are used for entertainment at parties, concerts. They are used by marching band conductors for evening performances, glow sticks are used in festivals. Glow sticks also serve multiple functions as toys, readily visible night-time warnings to motorists, yet another use is for balloon-carried light effects. Glow sticks are used to create special effects in low light photography. The Guinness Book of Records says the worlds largest glow stick was cracked at 9 ft 10 in tall and it was created using Plexiglass by KNIXS GmbH in Darmstadt Weiterstadt, Germany, on 29 June 2009
12.
Air-gap flash
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An air-gap flash is a photographic light source capable of producing sub-microsecond light flashes, allowing for high-speed photography. This is achieved by an electric discharge between two electrodes over the surface of a quartz tube. The distance between the electrodes is such that a discharge does not occur. To start the discharge a high-voltage pulse is applied on an electrode inside the quartz tube, the flash can be triggered electronically by being synchronised with an electronic detection device such as a microphone or an interrupted laser beam in order to illuminate a fast event. A sub-microsecond flash is fast enough to stop even a supersonic bullet in flight without noticeable motion blur. The person credited with popularising the flash is Harold Eugene Edgerton, william Henry Fox Talbot is said to have created the first spark-based flash photo, using a Leyden jar, the original form of the capacitor. Edgerton was one of the founders of EG&G company who sold an air-gap flash under the name Microflash 549, there are several commercial flashes available today. The aim of a flash is to be very fast. An air-gap flash system typically consists of a capacitor that is discharged through a gas, the speed of a flash is mainly determined by the time it takes to discharge the capacitor through the gas. This time is proportional to t d i s c h a r g e ∝ L C, in which L is the inductance, to be fast, both L and C must be kept small. The brightness of the flash is proportional to the energy stored in the capacitor, E = C V22 and this shows that high brightness calls for a large capacitance and a high voltage. Typical values are 0.05 µF capacitance,0.02 µH inductance,10 J energy,0.5 µs duration, air is preferred as a gas because it is fast. Xenon has a higher efficiency in turning energy into light. The spark is guided over a surface to improve the light output and benefit from the cooling capacity. This has an effect in the form of quartz erosion because of high energy discharge. Since the spark gap discharges in air generating a plasma, the spectrum shows both a continuum and spectral lines, mainly of nitrogen since air is 79% nitrogen, the spectrum is rich in UV but covers the entire visible range down to infra-red. When a quartz tube is used as ignition tube, it shows a clear phosphorescence in blue after the flash, amateur air-gap flash for ultra-high-speed photography by Niels Noordhoek MIT Edgerton center Scientific American article on air-gap flash
