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Array ( [0] => {{short description|Emission of light by a substance that has absorbed light}} [1] => {{distinguish|Inflorescence}} [2] => {{for|the album by Asobi Seksu|Fluorescence (album){{!}}''Fluorescence'' (album)}} [3] => {{Use dmy dates|date=October 2020}} [4] => [[File:Fluorescent minerals hg.jpg|thumb|right|Fluorescent minerals emit [[visible spectrum|visible light]] when exposed to [[ultraviolet]].]] [5] => [[File:Adaptive-Evolution-of-Eel-Fluorescent-Proteins-from-Fatty-Acid-Binding-Proteins-Produces-Bright-pone.0140972.g001.jpg|thumb|Fluorescent marine organisms]] [6] => [[File:Black light theatre Prague HILT 13.jpg|right|thumb|Fluorescent clothes used in [[black light theater]] production, [[Prague]] ]] [7] => [8] => '''Fluorescence''' is one of two kinds of emission of [[light]] by a substance that has absorbed light or other [[electromagnetic radiation]]. Fluorescence involves no change in electron spin multiplicity and generally it immediately follows absorption; [[phosphorescence]] involves spin change and is delayed. Thus fluorescent materials generally cease to glow nearly immediately when the radiation source stops, while [[phosphorescence|phosphorescent]] materials, which continue to emit light for some time after. [9] => [10] => Fluorescence is a form of [[luminescence]]. In most cases, the emitted light has a longer [[wavelength]], and therefore a lower [[photon]] [[energy]], than the absorbed radiation. A perceptible example of fluorescence occurs when the absorbed radiation is in the [[ultraviolet]] region of the [[electromagnetic spectrum]] (invisible to the human eye), while the emitted light is in the [[visible spectrum|visible region]]; this gives the fluorescent substance a distinct [[color]] that can only be seen when the substance has been exposed to [[blacklight|UV light]]. [11] => [12] => Fluorescence has many practical applications, including [[mineralogy]], [[gemology]], [[medicine]], chemical sensors ([[fluorescence spectroscopy]]), [[fluorescent labelling]], [[dye]]s, biological detectors, cosmic-ray detection, [[vacuum fluorescent display]]s, and [[cathode-ray tube]]s. Its most common everyday application is in ([[gas-discharge lamp|gas-discharge]]) [[fluorescent lamp]]s and [[LED lamps]], in which fluorescent coatings convert UV or blue light into longer-wavelengths resulting in [[White#White light|white light]] which can even appear indistinguishable from that of the traditional but energy- inefficient [[incandescent lamp]]. [13] => [14] => Fluorescence also occurs frequently in nature in some minerals and in many biological forms across all kingdoms of life. The latter may be referred to as ''biofluorescence'', indicating that the [[fluorophore]] is part of or is extracted from a living organism (rather than an inorganic [[dye]] or [[Staining|stain]]). But since fluorescence is due to a specific chemical, which can also be synthesized artificially in most cases, it is sufficient to describe the substance itself as ''fluorescent''. [15] => [16] => ==History== [17] => [[File:Lignum nephriticum - cup of Philippine lignum nephriticum, Pterocarpus indicus, and flask containing its fluorescent solution Hi.jpg|thumb|left|upright|A cup made from the wood of the narra tree (''[[Pterocarpus indicus]]'') beside a flask containing its fluorescent [[Solution (chemistry)|solution]] ''[[Lignum nephriticum]]''.]] [18] => [[File:Matlaline structure.svg|thumb|right|Matlaline, the fluorescent substance in the wood of the tree ''Eysenhardtia polystachya'']] [19] => Fluorescence was observed long before it was named and understood. [20] => {{cite journal [21] => | last1 = Valeur | first1 = B. [22] => | last2 = Berberan-Santos | first2 = M.R.N. [23] => | year = 2011 [24] => | title = A brief history of fluorescence and phosphorescence before the emergence of quantum theory [25] => | journal = Journal of Chemical Education [26] => | volume = 88 | issue = 6 | pages = 731–738 [27] => | s2cid = 55366778 | doi = 10.1021/ed100182h [28] => | bibcode = 2011JChEd..88..731V [29] => }} [30] => [31] => An early observation of fluorescence was known to the Aztecs and described in 1560 by [[Bernardino de Sahagún]] and in 1565 by [[Nicolás Monardes]] in the [[infusion]] known as ''[[lignum nephriticum]]'' ([[Latin]] for "kidney wood"). It was derived from the wood of two tree species, ''[[Pterocarpus indicus]]'' and ''[[Eysenhardtia polystachya]]''. [32] => {{cite journal [33] => |last1 = Acuña |first1 = A. Ulises |last2 = Amat-Guerri |first2 = Francisco [34] => |last3 = Morcillo |first3 = Purificación |last4 = Liras |first4 = Marta [35] => |last5 = Rodríguez |first5 = Benjamín [36] => |year = 2009 [37] => |title = Structure and formation of the fluorescent compound of ''lignum nephriticum'' [38] => |journal = Organic Letters [39] => |volume = 11 |issue = 14 |pages = 3020–3023 [40] => |doi = 10.1021/ol901022g |pmid = 19586062 [41] => |url = http://202.127.145.151/siocl/siocl_0001/HHJdatabank/090707ol-6.pdf [42] => |url-status = live [43] => |archive-url = https://web.archive.org/web/20130728224629/http://202.127.145.151/siocl/siocl_0001/HHJdatabank/090707ol-6.pdf [44] => |archive-date = 28 July 2013 [45] => }} [46] => [47] => {{cite book [48] => |author=Safford, W.E. |author-link=William Edwin Safford [49] => |year=1916 [50] => |chapter=''Lignum nephriticum'' [51] => |title=Annual report of the Board of Regents of the Smithsonian Institution [52] => |location=Washington, DC [53] => |publisher=U.S. Government Printing Office [54] => |pages=271–298 [55] => |chapter-url=https://archive.org/download/annualreportofbo1915smitfo/annualreportofbo1915smitfo.pdf |archive-url=https://web.archive.org/web/20130729063130/http://archive.org/download/annualreportofbo1915smitfo/annualreportofbo1915smitfo.pdf |archive-date=2013-07-29 |url-status=live [56] => }} [57] => [58] => {{cite journal [59] => | last1 = Muyskens | first1 = M. [60] => | last2 = Vitz | first2 = Ed [61] => | year = 2006 [62] => | title = The fluorescence of ''lignum nephriticum'': A flash back to the past and a simple demonstration of natural substance fluorescence [63] => | journal = Journal of Chemical Education [64] => | volume = 83 | issue = 5 | page = 765 [65] => | doi = 10.1021/ed083p765 [66] => | bibcode = 2006JChEd..83..765M [67] => }} [68] => [69] => The chemical compound responsible for this fluorescence is matlaline, which is the oxidation product of one of the [[flavonoid]]s found in this wood. [70] => [71] => In 1819, [[Edward Daniel Clarke|E.D. Clarke]] [72] => {{cite journal [73] => |author=Clarke, E.D. |author-link=Edward Daniel Clarke [74] => |year=1819 [75] => |title=Account of a newly discovered variety of green fluor spar, of very uncommon beauty, and with remarkable properties of colour and phosphorescence [76] => |journal=The Annals of Philosophy [77] => |volume=14 |pages=34–36 [78] => |quote=The finer crystals are perfectly transparent. Their colour by transmitted light is an intense ''emerald green''; but by reflected light, the colour is a deep ''sapphire blue''. [79] => |url=https://books.google.com/books?id=KWc7AQAAIAAJ&pg=PA34 [80] => |url-status=live [81] => |archive-url=https://web.archive.org/web/20170117092607/https://books.google.com/books?id=KWc7AQAAIAAJ&pg=PA34 [82] => |archive-date=17 January 2017 [83] => }} [84] => [85] => and in 1822 [[René Just Haüy]] [86] => [87] => {{cite book [88] => |author=Haüy, R.J. |author-link=René Just Haüy [89] => |title=Traité de Minéralogie |language=fr [90] => |trans-title=Treatise on Mineralogy [91] => |edition=2nd [92] => |place=Paris, France [93] => |publisher=Bachelier and Huzard [94] => |year=1822 [95] => |volume=1 |page=[https://books.google.com/books?id=MvcTAAAAQAAJ&pg=PA512 512] [96] => |url=https://books.google.com/books?id=MvcTAAAAQAAJ |via=Google Books [97] => |archive-url=https://web.archive.org/web/20170117122039/https://books.google.com/books?id=MvcTAAAAQAAJ&pg=PA512 [98] => |archive-date=17 January 2017 [99] => }} [100] => [101] => described some varieties of [[fluorite]]s that had a different color depending if the light was reflected or (apparently) transmitted; Haüy's incorrectly viewed the effect as light scattering similar to [[opalescence]].{{rp|loc=Fig.5|q=The green color is due to Sm2+ absorption (in the blue and in the red) (14), whereas the deep blue color is due to Eu2+ fluorescence...}} In 1833 [[Sir David Brewster]] described a similar effect in [[chlorophyll]] which he also considered a form of opalescence. [102] => {{cite journal [103] => |author=Brewster, D. |author-link=Sir David Brewster [104] => |year=1834 [105] => |title=On the colours of natural bodies [106] => |journal=Transactions of the Royal Society of Edinburgh [107] => |volume=12 |issue=2 |pages=538–545, esp. 542 [108] => |doi=10.1017/s0080456800031203 [109] => |s2cid=101650922 [110] => |url=https://books.google.com/books?id=I_UQAAAAIAAJ&pg=PA538 [111] => |url-status=live [112] => |archive-url=https://web.archive.org/web/20170117120622/https://books.google.com/books?id=I_UQAAAAIAAJ&pg=PA538 [113] => |archive-date=17 January 2017 [114] => }} [115] => On page 542, Brewster mentions that when white light passes through an alcohol solution of chlorophyll, red light is reflected from it. [116] => [117] => [[Sir John Herschel]] studied [[quinine]] in 1845 [118] => {{cite journal [119] => |author=Herschel, J. |author-link=Sir John Herschel [120] => |year=1845 [121] => |title=On a case of superficial colour presented by a homogeneous liquid internally colourless [122] => |journal=Philosophical Transactions of the Royal Society of London [123] => |volume=135 |pages=143–145 [124] => |doi=10.1098/rstl.1845.0004 [125] => |doi-access=free [126] => |url=https://books.google.com/books?id=GmwOAAAAIAAJ&pg=PA143 [127] => |url-status=live [128] => |archive-url=https://web.archive.org/web/20161224220539/https://books.google.com/books?id=GmwOAAAAIAAJ&pg=PA143 [129] => |archive-date=24 December 2016 [130] => }} [131] => [132] => {{cite journal [133] => |author=Herschel, J. |author-link=Sir John Herschel [134] => |year=1845 [135] => |title=On the epipŏlic dispersion of light, being a supplement to a paper entitled, "On a case of superficial colour presented by a homogeneous liquid internally colourless" [136] => |journal=Philosophical Transactions of the Royal Society of London [137] => |volume=135 |pages=147–153 [138] => |doi=10.1098/rstl.1845.0005 [139] => |doi-access=free [140] => |url=https://books.google.com/books?id=GmwOAAAAIAAJ&pg=PA147 [141] => |url-status=live [142] => |archive-url=https://web.archive.org/web/20170117093409/https://books.google.com/books?id=GmwOAAAAIAAJ&pg=PA147 [143] => |archive-date=17 January 2017 [144] => }} [145] => and came to a different incorrect conclusion. [146] => [147] => In 1842, [[A. E. Becquerel|A.E. Becquerel]] observed that [[calcium sulfide]] emits light after being exposed to solar [[ultraviolet]], making him the first to state that the emitted light is of longer wavelength than the incident light. While his observation of [[photoluminescence]] was similar to that described 10 years later by Stokes, who observed a fluorescence of a solution of [[quinine]], the phenomenon that Becquerel described with calcium sulfide is now called [[phosphorescence]]. [148] => [149] => In his 1852 paper on the "Refrangibility" ([[wavelength]] change) of light, [[George Gabriel Stokes]] described the ability of [[fluorite|fluorspar]], [[uranium glass]] and many other substances to change invisible light beyond the violet end of the visible spectrum into visible light. He named this phenomenon ''fluorescence'' [150] => : "I am almost inclined to coin a word, and call the appearance ''fluorescence'', from fluor-spar [i.e., fluorite], as the analogous term ''opalescence'' is derived from the name of a mineral." [151] => {{cite journal [152] => |author = Stokes, G.G. |author-link=George Gabriel Stokes [153] => |year = 1852 [154] => |title = On the change of refrangibility of light [155] => |journal = Philosophical Transactions of the Royal Society of London [156] => |volume = 142 |pages = 463–562, esp. 479 [157] => |doi = 10.1098/rstl.1852.0022 |doi-access= free [158] => |url = https://books.google.com/books?id=CE9FAAAAcAAJ&pg=PA463 [159] => |url-status = live [160] => |archive-url = https://web.archive.org/web/20170117061614/https://books.google.com/books?id=CE9FAAAAcAAJ&pg=PA463 [161] => |archive-date = 17 January 2017 [162] => }} [163] => {{rp|style=ama|p= 479, footnote}} [164] => [165] => Neither Becquerel nor Stokes understood one key aspect of photoluminescence: the critical difference from [[incandescence]], the emission of light by heated material. To distinguish it from incandescence, in the late 1800s, [[Gustav Wiedemann]] proposed the term [[luminescence]] to designate any emission of light more intense than expected from the source’s temperature. [166] => [167] => {{clear}} [168] => [169] => == Physical principles == [170] => === Mechanism === [171] => [[File:Ruby ball fluorescence @ 520nm laser illumination.jpg|thumb|A ruby [[ball lens]] atop a green laser-pointer. The green beam [[Vergence (optics)|converges]] into a cone within the crystal and is focused to a point on top. The green light is absorbed and spontaneously remitted as red light. Not all of the light is absorbed, and a small portion of the 520 nm laser light transmits through the top, unaltered by the ruby's red color.]] [172] => Fluorescence occurs when an excited molecule, atom, or [[nanostructure]], relaxes to a lower energy state (usually the [[ground state]]) through emission of a [[photon]] without a change in [[electron spin]]. When the initial and final states have different multiplicity (spin), the phenomenon is termed [[phosphorescence]].{{Cite journal |last=Verhoeven |first=J. W. |date=1996-01-01 |title=Glossary of terms used in photochemistry (IUPAC Recommendations 1996) |url=https://www.degruyter.com/document/doi/10.1351/pac199668122223/html |journal=Pure and Applied Chemistry |language=de |volume=68 |issue=12 |pages=2223–2286 |doi=10.1351/pac199668122223 |issn=1365-3075}} [173] => [174] => The ground state of most molecules is a [[singlet state]], denoted as S₀. A notable exception is [[Oxygen|molecular oxygen]], which has a [[Triplet state|triplet]] ground state. Absorption of a photon of energy

h \nu_{ex}

results in an excited state of the same multiplicity (spin) of the ground state, usually a singlet (S_n with n > 0). In solution, states with n > 1 relax rapidly to the lowest vibrational level of the first excited state (S₁) by transferring energy to the solvent molecules through non-radiative processes, including internal conversion followed by vibrational relaxation, in which the energy is dissipated as [[heat]]. Therefore, most commonly, fluorescence occurs from the first singlet excited state, S₁. Fluorescence is the emission of a photon accompanying the relaxation of the excited state to the ground state. Fluorescence photons are lower in energy (

h \nu_{em}

) compared to the energy of the photons used to generate the excited state (

h \nu_{ex}

) [175] => [176] => * Excitation:

\mathrm{S}_0 + h \nu_\text{ex} \to \mathrm{S}_1

[177] => * Fluorescence (emission):

\mathrm{S}_1 \to \mathrm{S}_0  + h \nu_\text{em}

[178] => In each case the photon energy

E

is proportional to its [[frequency]]

\nu

according to

E=h\nu

, where

h

is the [[Planck constant]]. [179] => [180] => The excited state S₁ can relax by other mechanisms that do not involve the emission of light. These processes, called non-radiative processes, compete with fluorescence emission and decrease its efficiency. Examples include [[Internal conversion (chemistry)|internal conversion]], [[intersystem crossing]] to the triplet state, and energy transfer to another molecule. An example of energy transfer is [[Förster resonance energy transfer]]. Relaxation from an excited state can also occur through collisional [[Quenching (fluorescence)|quenching]], a process where a molecule (the quencher) collides with the fluorescent molecule during its excited state lifetime. Molecular [[oxygen]] (O₂) is an extremely efficient quencher of fluorescence just because of its unusual triplet ground state. [181] => [182] => === Quantum yield === [183] => 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.{{rp|style=ama|p= 10}} [184] => {{cite book [185] => |author1=Valeur, Bernard [186] => |author2=Berberan-Santos, Mario [187] => |year=2012 [188] => |title=Molecular Fluorescence: Principles and applications [189] => |publisher=Wiley-VCH [190] => |isbn=978-3-527-32837-6 [191] => |page=64 [192] => }} [193] => [194] => :

\Phi = \frac {\text{Number of photons emitted}} {\text{Number of photons absorbed}}

[195] => [196] => The maximum possible fluorescence quantum yield is 1.0 (100%); each [[photon]] absorbed results in a photon emitted. Compounds with quantum yields of 0.10 are still considered quite fluorescent. Another way to define the quantum yield of fluorescence is by the rate of excited state decay: [197] => :

\Phi = \frac{ { k}_{ f} }{ \sum_{i}{ k}_{i } }

[198] => where

{ k}_{ f}

is the rate constant of [[spontaneous emission]] of radiation and [199] => :

\sum_{i}{ k}_{i }

[200] => is the sum of all rates of excited state decay. Other rates of excited state decay are caused by mechanisms other than photon emission and are, therefore, often called "non-radiative rates", which can include: [201] => * dynamic collisional quenching [202] => * near-field dipole–dipole interaction (or [[resonance energy transfer]]) [203] => * internal conversion [204] => * [[intersystem crossing]] [205] => [206] => Thus, if the rate of any pathway changes, both the excited state lifetime and the fluorescence quantum yield will be affected. [207] => [208] => Fluorescence quantum yields are measured by comparison to a standard.{{Cite journal |last=Levitus |first=Marcia |date=2020-04-22 |title=Tutorial: measurement of fluorescence spectra and determination of relative fluorescence quantum yields of transparent samples |url=https://doi.org/10.1088/2050-6120/ab7e10|journal=Methods and Applications in Fluorescence |volume=8 |issue=3 |pages=033001 |doi=10.1088/2050-6120/ab7e10 |pmid=32150732 |bibcode=2020MApFl...8c3001L |s2cid=212653274 |issn=2050-6120 |access-date=9 June 2021 |archive-date=4 May 2022|archive-url=https://web.archive.org/web/20220504144923/https://iopscience.iop.org/article/10.1088/2050-6120/ab7e10 |url-status=live}} The [[quinine]] salt ''quinine sulfate'' in a [[sulfuric acid]] solution was regarded as the most common fluorescence standard, [209] => {{cite journal [210] => |last=Brouwer |first=Albert M. [211] => |date=2011-08-31 [212] => |title=Standards for photoluminescence quantum yield measurements in solution [213] => |series=IUPAC Technical Report [214] => |journal=Pure and Applied Chemistry [215] => |volume=83 |issue=12 |pages=2213–2228 [216] => |doi=10.1351/PAC-REP-10-09-31 [217] => |s2cid=98138291 |issn=1365-3075 [218] => |doi-access=free [219] => }} [220] => [221] => however, a recent study revealed that the fluorescence quantum yield of this solution is strongly affected by the temperature, and should no longer be used as the standard solution. The quinine in 0.1 [[mole (unit)|M]] perchloric acid ({{nowrap|1=Φ = 0.60}}) shows no temperature dependence up to 45 °C, therefore it can be considered as a reliable standard solution. [222] => {{cite journal [223] => |last1=Nawara |first1=Krzysztof [224] => |last2=Waluk |first2=Jacek [225] => |date=2019-04-16 [226] => |title=Goodbye to quinine in sulfuric acid solutions as a fluorescence quantum yield standard [227] => |journal=Analytical Chemistry |language=en [228] => |volume=91 |issue=8 |pages=5389–5394 [229] => |doi=10.1021/acs.analchem.9b00583 [230] => |pmid=30907575 |s2cid=85501014 |issn=0003-2700 [231] => |url=https://pubs.acs.org/doi/10.1021/acs.analchem.9b00583 [232] => |url-status=live [233] => |archive-url=https://web.archive.org/web/20210207194942/https://pubs.acs.org/doi/10.1021/acs.analchem.9b00583 [234] => |archive-date=7 February 2021 [235] => }} [236] => [237] => [238] => === Lifetime === [239] => [[File:Jablonski Diagram of Fluorescence Only-en.svg|thumb|[[Jablonski diagram]]. After an electron absorbs a high-energy photon the system is excited electronically and vibrationally. The system relaxes vibrationally, and eventually fluoresces at a longer wavelength than the original high-energy photon had.]] [240] => [241] => The fluorescence lifetime refers to the average time the molecule stays in its excited state before emitting a photon. Fluorescence typically follows [[first-order kinetics]]: [242] => :

\left[S_1 \right] = \left[S_1 \right]_0 e^{-\Gamma t}

[243] => where

\left[S_1 \right]

is the concentration of excited state molecules at time

t

\left[S_1 \right]_0

is the initial concentration and [[Gamma|

\Gamma

]] is the decay rate or the inverse of the fluorescence lifetime. This is an instance of [[exponential decay]]. Various radiative and non-radiative processes can de-populate the excited state. In such case the total decay rate is the sum over all rates: [244] => :

\Gamma_{tot}=\Gamma_{rad} + \Gamma_{nrad}

[245] => where

\Gamma_{tot}

is the total decay rate,

\Gamma_{rad}

the radiative decay rate and

\Gamma_{nrad}

the non-radiative decay rate. It is similar to a first-order chemical reaction in which the first-order rate constant is the sum of all of the rates (a parallel kinetic model). If the rate of spontaneous emission, or any of the other rates are fast, the lifetime is short. For commonly used fluorescent compounds, typical excited state decay times for photon emissions with energies from the [[Ultraviolet|UV]] to [[near infrared]] are within the range of 0.5 to 20 [[nanoseconds]]. The fluorescence lifetime is an important parameter for practical applications of fluorescence such as [[fluorescence resonance energy transfer]] and [[fluorescence-lifetime imaging microscopy]]. [246] => [247] => === Jablonski diagram === [248] => The [[Jablonski diagram]] describes most of the relaxation mechanisms for excited state molecules. The diagram alongside shows how fluorescence occurs due to the relaxation of certain excited electrons of a molecule.[http://pharmaxchange.info/press/2013/03/animation-for-the-principle-of-fluorescence-and-uv-visible-absorbance/ "Animation for the Principle of Fluorescence and UV-Visible Absorbance"] {{webarchive|url=https://web.archive.org/web/20130609034835/http://pharmaxchange.info/press/2013/03/animation-for-the-principle-of-fluorescence-and-uv-visible-absorbance/ |date=9 June 2013 }}. ''PharmaXChange.info''. [249] => [250] => === Fluorescence anisotropy === [251] => Fluorophores are more likely to be excited by photons if the transition moment of the fluorophore is parallel to the electric vector of the photon.{{rp|style=ama|pp= 12–13}} The polarization of the emitted light will also depend on the transition moment. The transition moment is dependent on the physical orientation of the fluorophore molecule. For fluorophores in solution, the intensity and polarization of the emitted light is dependent on rotational diffusion. Therefore, anisotropy measurements can be used to investigate how freely a fluorescent molecule moves in a particular environment. [252] => [253] => Fluorescence anisotropy can be defined quantitatively as [254] => :

r = {I_\parallel - I_\perp \over I_\parallel + 2I_\perp}

[255] => where

I_\parallel

is the emitted intensity parallel to the polarization of the excitation light and

I_\perp

is the emitted intensity perpendicular to the polarization of the excitation light. [256] => [257] => Anisotropy is independent of the intensity of the absorbed or emitted light, it is the property of the light, so photobleaching of the dye will not affect the anisotropy value as long as the signal is detectable. [258] => [259] => === Fluorescence === [260] => [[File:US $20 under blacklight.jpg|thumb|Fluorescent security strip in a US twenty dollar bill under UV light]] [261] => Strongly fluorescent pigments often have an unusual appearance which is often described colloquially as a "neon color" (originally "day-glo" in the late 1960s, early 1970s). This phenomenon was termed "Farbenglut" by [[Hermann von Helmholtz]] and "fluorence" by Ralph M. Evans. It is generally thought to be related to the high brightness of the color relative to what it would be as a component of white. Fluorescence shifts energy in the incident illumination from shorter wavelengths to longer (such as blue to yellow) and thus can make the fluorescent color appear brighter (more saturated) than it could possibly be by reflection alone.{{cite journal|last1=Schieber|first1=Frank|s2cid=2439728|title=Modeling the Appearance of Fluorescent Colors|journal=Proceedings of the Human Factors and Ergonomics Society Annual Meeting|date=October 2001|volume=45|issue=18|pages=1324–1327|doi=10.1177/154193120104501802}} [262] => [263] => == Rules == [264] => There are several general [[rule of thumb|rules]] that deal with fluorescence. Each of the following rules have exceptions but they are useful guidelines for understanding fluorescence (these rules do not necessarily apply to [[two-photon absorption]]). [265] => [266] => === Kasha's rule === [267] => [[Kasha's rule]] states that the luminesce (fluorescence or phosphorescence) of a molecule will be emitted only from the lowest excited state of its given multiplicity. [[International Union of Pure and Applied Chemistry|IUPAC]].PAC, 2007, 79, 293. (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 360 https://goldbook.iupac.org/terms/view/K03370 Vavilov's rule (a logical extension of Kasha's rule thusly called Kasha–Vavilov rule) dictates that the quantum yield of luminescence is independent of the wavelength of exciting radiation and is proportional to the absorbance of the excited wavelength.[[International Union of Pure and Applied Chemistry|IUPAC]]. [http://goldbook.iupac.org/K03371.html – Compendium of Chemical Terminology, 2nd ed. (the "Gold Book")] {{webarchive|url=https://web.archive.org/web/20120321031448/http://goldbook.iupac.org/K03371.html |date=21 March 2012 }}. Compiled by McNaught, A.D. and Wilkinson, A. Blackwell Scientific Publications, Oxford, 1997. Kasha's rule does not always apply and is violated by simple molecules, such an example is azulene.Excited-State (Anti)Aromaticity Explains Why Azulene Disobeys Kasha’s Rule [268] => David Dunlop, Lucie Ludvíková, Ambar Banerjee, Henrik Ottosson, and Tomáš Slanina [269] => Journal of the American Chemical Society 2023 145 (39), 21569-21575 [270] => DOI: 10.1021/jacs.3c07625 A somewhat more reliable statement, although still with exceptions, would be that the fluorescence spectrum shows very little dependence on the wavelength of exciting radiation.{{Cite journal |last1=Qian |first1=Hai |last2=Cousins |first2=Morgan E. |last3=Horak |first3=Erik H. |last4=Wakefield |first4=Audrey |last5=Liptak |first5=Matthew D. |last6=Aprahamian |first6=Ivan |date=January 2017 |title=Suppression of Kasha's rule as a mechanism for fluorescent molecular rotors and aggregation-induced emission |url=https://www.nature.com/articles/nchem.2612 |journal=Nature Chemistry |language=en |volume=9 |issue=1 |pages=83–87 |doi=10.1038/nchem.2612 |pmid=27995926 |s2cid=42798987 |issn=1755-4330}} [271] => [272] => === Mirror image rule === [273] => [[File:Stokes shift- Rh6G.png|thumb|The fluorescent dye, [[rhodamine 6G]], is commonly used in applications such as [[highlighter pen]]s, [[dye laser]]s, and automotive leak detection. The absorption profile is a mirror of the emission profile.]] [274] => For many fluorophores the absorption spectrum is a mirror image of the emission spectrum. [275] =>
[276] => {{cite book [277] => |author=Lakowicz, Joseph R. [278] => |year=1999 [279] => |title=Principles of Fluorescence Spectroscopy [280] => |publisher=Kluwer Academic / Plenum Publishers [281] => |isbn=978-0-387-31278-1 [282] => }} [283] => {{rp|style=ama|pp= 6–8}} [284] => This is known as the mirror image rule and is related to the [[Franck–Condon principle]] which states that electronic transitions are vertical, that is energy changes without distance changing as can be represented with a vertical line in Jablonski diagram. This means the nucleus does not move and the vibration levels of the excited state resemble the vibration levels of the ground state. [285] => [286] => === Stokes shift === [287] => {{main|Stokes shift}} [288] => In general, emitted fluorescence light has a longer wavelength and lower energy than the absorbed light.{{rp|style=ama|pp= 6–7}} This phenomenon, known as [[Stokes shift]], is due to energy loss between the time a photon is absorbed and when a new one is emitted. The causes and magnitude of Stokes shift can be complex and are dependent on the fluorophore and its environment. However, there are some common causes. It is frequently due to non-radiative decay to the lowest vibrational energy level of the excited state. Another factor is that the emission of fluorescence frequently leaves a fluorophore in a higher vibrational level of the ground state. [289] => [290] => == In nature == [291] => [[File:Fluorescent Coral Movie.gif|thumb|Fluorescent coral]] [292] => {{main|Fluorescence in the life sciences}} [293] => There are many natural compounds that exhibit fluorescence, and they have a number of applications. Some deep-sea animals, such as the [[greeneye]], have fluorescent structures. [294] => [295] => === Compared to bioluminescence and biophosphorescence === [296] => ==== Fluorescence ==== [297] => Fluorescence is the phenomenon of absorption of [[electromagnetic radiation|electromagnetic]] radiation, typically from ultraviolet or [[visible light]], by a molecule and the subsequent emission of a photon of a lower energy (smaller frequency, longer wavelength). This causes the light that is emitted to be a different color than the light that is absorbed. Stimulating light excites an [[electron]] to an excited state. When the molecule returns to the ground state, it releases a photon, which is the fluorescent emission. The excited state lifetime is short, so emission of light is typically only observable when the absorbing light is on. Fluorescence can be of any wavelength but is often more significant when emitted photons are in the visible spectrum. When it occurs in a living organism, it is sometimes called biofluorescence. Fluorescence should not be confused with bioluminescence and biophosphorescence.{{cite web|title=Fluorescence in marine organisms|url=http://gestaltswitchexpeditions.com/fluorescence-in-marine-orga/|website=Gestalt Switch Expeditions|url-status=dead|archive-url=https://web.archive.org/web/20150221070425/http://www.gestaltswitchexpeditions.com/fluorescence-in-marine-orga/|archive-date=21 February 2015}} Pumpkin toadlets that live in the Brazilian Atlantic forest are fluorescent.{{Cite news|url=https://www.business-standard.com/article/pti-stories/fluorescence-discovered-in-tiny-brazilian-frogs-119032900584_1.html|title=Fluorescence discovered in tiny Brazilian frogs|agency=Press Trust of India|date=2019-03-29|work=Business Standard India|access-date=2019-03-30|archive-date=30 March 2019|archive-url=https://web.archive.org/web/20190330124158/https://www.business-standard.com/article/pti-stories/fluorescence-discovered-in-tiny-brazilian-frogs-119032900584_1.html|url-status=live}} [298] => [299] => ==== Bioluminescence ==== [300] => [[Bioluminescence]] differs from fluorescence in that it is the natural production of light by chemical reactions within an organism, whereas fluorescence is the absorption and reemission of light from the environment. [[Firefly|Fireflies]] and [[anglerfish]] are two examples of bioluminescent organisms.{{cite web|url=https://earthnworld.com/top-10-amazing-bioluminescent-animals-planet-earth/|title=Top 10 Amazing Bioluminescent Animals on Planet Earth|last=Utsav|date=2017-12-02|website=Earth and World|language=en-US|access-date=2019-03-30|archive-date=30 March 2019|archive-url=https://web.archive.org/web/20190330124620/https://earthnworld.com/top-10-amazing-bioluminescent-animals-planet-earth/|url-status=live}} To add to the potential confusion, some organisms are both bioluminescent and fluorescent, like the sea pansy [[Renilla reniformis]], where bioluminescence serves as the light source for fluorescence.{{cite journal |last1=Ward |first1=William W. |last2=Cormier |first2=Milton J. |title=Energy Transfer Via Protein–Protein Interaction in Renilla Bioluminescence |journal=Photochemistry and Photobiology |date=1978 |volume=27 |issue=4 |pages=389–396 |doi=10.1111/j.1751-1097.1978.tb07621.x|s2cid=84887904 }} [301] => [302] => ==== Phosphorescence ==== [303] => [[Phosphorescence]] is similar to fluorescence in its requirement of light wavelengths as a provider of excitation energy. The difference here lies in the relative stability of the energized electron. Unlike with fluorescence, in phosphorescence the electron retains stability, emitting light that continues to "glow in the dark" even after the stimulating light source has been removed. For example, [[phosphorescence|glow-in-the-dark]] stickers are phosphorescent, but there are no truly ''biophosphorescent'' animals known.{{cite web|url=http://www.seasky.org/deep-sea/firefly-squid.html|title=Firefly Squid – Deep Sea Creatures on Sea and Sky|website=www.seasky.org|access-date=2019-03-30|archive-date=28 June 2019|archive-url=https://web.archive.org/web/20190628025334/http://www.seasky.org/deep-sea/firefly-squid.html|url-status=live}} [304] => [305] => === Mechanisms === [306] => ==== Epidermal chromatophores ==== [307] => Pigment cells that exhibit fluorescence are called fluorescent chromatophores, and function somatically similar to regular [[chromatophore]]s. These cells are dendritic, and contain pigments called fluorosomes. These pigments contain fluorescent proteins which are activated by K+ (potassium) ions, and it is their movement, aggregation, and dispersion within the fluorescent chromatophore that cause directed fluorescence patterning. [308] => {{cite journal [309] => | pmid = 11041206 [310] => | year = 2000 [311] => | last1 = Fujii [312] => | first1 = R [313] => | title = The regulation of motile activity in fish chromatophores [314] => | journal = Pigment Cell Research [315] => | volume = 13 [316] => | issue = 5 [317] => | pages = 300–19 [318] => | doi=10.1034/j.1600-0749.2000.130502.x [319] => }} Fluorescent cells are innervated the same as other chromatophores, like melanophores, pigment cells that contain [[melanin]]. Short term fluorescent patterning and signaling is controlled by the nervous system. Fluorescent chromatophores can be found in the skin (e.g. in fish) just below the epidermis, amongst other chromatophores. [320] => [321] => Epidermal fluorescent cells in fish also respond to hormonal stimuli by the α–MSH and MCH hormones much the same as melanophores. This suggests that fluorescent cells may have color changes throughout the day that coincide with their [[circadian rhythm]].{{Cite journal | doi = 10.1093/icb/13.3.885| title = Endocrine Regulation of Pigmentation in Fish| journal = Integrative and Comparative Biology| volume = 13| issue = 3| pages = 885–894| year = 1973| last1 = Abbott | first1 = F. S. | doi-access = free}} Fish may also be sensitive to [[cortisol]] induced [[stress response]]s to environmental stimuli, such as interaction with a predator or engaging in a mating ritual. [322] => [323] => === Phylogenetics === [324] => ==== Evolutionary origins ==== [325] => The incidence of fluorescence across the [[tree of life]] is widespread, and has been studied most extensively in cnidarians and fish. The phenomenon appears to have evolved multiple times in multiple [[Taxon|taxa]] such as in the anguilliformes (eels), gobioidei (gobies and cardinalfishes), and tetradontiformes (triggerfishes), along with the other taxa discussed later in the article. Fluorescence is highly genotypically and phenotypically variable even within ecosystems, in regards to the wavelengths emitted, the patterns displayed, and the intensity of the fluorescence. Generally, the species relying upon camouflage exhibit the greatest diversity in fluorescence, likely because camouflage may be one of the uses of fluorescence.{{Cite journal | last1 = Sparks | first1 = J. S. | last2 = Schelly | first2 = R. C. | last3 = Smith | first3 = W. L. | last4 = Davis | first4 = M. P. | last5 = Tchernov | first5 = D. | last6 = Pieribone | first6 = V. A. | last7 = Gruber | first7 = D. F. | editor1-last = Fontaneto | editor1-first = Diego | title = The Covert World of Fish Biofluorescence: A Phylogenetically Widespread and Phenotypically Variable Phenomenon | doi = 10.1371/journal.pone.0083259 | journal = PLOS ONE| volume = 9 | issue = 1 | pages = e83259 | year = 2014 | pmid = 24421880| pmc = 3885428|bibcode = 2014PLoSO...983259S | doi-access = free }} [326] => [327] => [[File:Observed occurrences of green and red biofluorescence in Actinopterygii - journal.pone.0083259.g002.png|thumb|alt=Observed occurrences of green and red biofluorescence in Actinopterygii|Fluorescence has multiple origins in the tree of life. This diagram displays the origins within actinopterygians (ray finned fish).]] [328] => [329] => It is suspected by some scientists that [[Green fluorescent protein|GFPs]] and GFP-like proteins began as electron donors activated by light. These electrons were then used for reactions requiring light energy. Functions of fluorescent proteins, such as protection from the sun, conversion of light into different wavelengths, or for signaling are thought to have evolved secondarily.{{cite web|last1=Beyer|first1=Steffen|title=Biology of underwater fluorescence|url=https://translate.google.com/translate?sl=de&tl=en&prev=_t&hl=en&ie=UTF-8&u=http://www.fluopedia.org/publications/deutsch/biologie/|website=Fluopedia.org|access-date=19 January 2022|archive-date=30 July 2020|archive-url=https://web.archive.org/web/20200730070159/https://translate.google.com/translate?sl=de&tl=en&prev=_t&hl=en&ie=UTF-8&u=http%3A%2F%2Fwww.fluopedia.org%2Fpublications%2Fdeutsch%2Fbiologie%2F|url-status=live}} [330] => [331] => ==== Adaptive functions ==== [332] => Currently, relatively little is known about the functional significance of fluorescence and fluorescent proteins. However, it is suspected that fluorescence may serve important functions in signaling and communication, [[mating]], lures, [[camouflage]], [[UV protection]] and antioxidation, photoacclimation, [[dinoflagellate]] regulation, and in coral health.{{cite journal|last1=Haddock|first1=S. H. D.|last2=Dunn|first2=C. W.|title=Fluorescent proteins function as a prey attractant: experimental evidence from the hydromedusa Olindias formosus and other marine organisms|journal=Biology Open|volume=4|issue=9|year=2015|pages=1094–1104|issn=2046-6390|doi=10.1242/bio.012138|pmid=26231627|pmc=4582119}} [333] => [334] => === Aquatic === [335] => Water absorbs light of long wavelengths, so less light from these wavelengths reflects back to reach the eye. Therefore, warm colors from the visual light spectrum appear less vibrant at increasing depths. Water scatters light of shorter wavelengths above violet, meaning cooler colors dominate the visual field in the [[photic zone]]. Light intensity decreases 10 fold with every 75 m of depth, so at depths of 75 m, light is 10% as intense as it is on the surface, and is only 1% as intense at 150 m as it is on the surface. Because the water filters out the wavelengths and intensity of water reaching certain depths, different proteins, because of the wavelengths and intensities of light they are capable of absorbing, are better suited to different depths. Theoretically, some fish eyes can detect light as deep as 1000 m. At these depths of the aphotic zone, the only sources of light are organisms themselves, giving off light through chemical reactions in a process called bioluminescence. [336] => [337] => Fluorescence is simply defined as the absorption of electromagnetic radiation at one [[wavelength]] and its reemission at another, lower energy wavelength. Thus any type of fluorescence depends on the presence of external sources of light. Biologically functional fluorescence is found in the photic zone, where there is not only enough light to cause fluorescence, but enough light for other organisms to detect it.{{cite journal|last1=Mazel|first1=Charles|title=Method for Determining the Contribution of Fluorescence to an Optical Signature, with Implications for Postulating a Visual Function|journal=Frontiers in Marine Science|volume=4|year=2017|issn=2296-7745|doi=10.3389/fmars.2017.00266|doi-access=free}} [338] => The visual field in the photic zone is naturally blue, so colors of fluorescence can be detected as bright reds, oranges, yellows, and greens. Green is the most commonly found color in the marine spectrum, yellow the second most, orange the third, and red is the rarest. Fluorescence can occur in organisms in the aphotic zone as a byproduct of that same organism's bioluminescence. Some fluorescence in the aphotic zone is merely a byproduct of the organism's tissue biochemistry and does not have a functional purpose. However, some cases of functional and adaptive significance of fluorescence in the aphotic zone of the deep ocean is an active area of research.{{cite web|last1=Matz|first1=M.|title=Fluorescence: The Secret Color of the Deep|url=http://oceanexplorer.noaa.gov/explorations/05deepscope/background/fluorescence/fluorescence.html|publisher=Office of Ocean Exploration and Research, U.S. National Oceanic and Atmospheric Administration|url-status=live|archive-url=https://web.archive.org/web/20141031213647/http://oceanexplorer.noaa.gov/explorations/05deepscope/background/fluorescence/fluorescence.html|archive-date=31 October 2014}} [339] => [340] => ==== Photic zone ==== [341] => {{main|Photic zone}} [342] => [343] => ===== Fish ===== [344] => [[File:Diversity of fluorescent patterns and colors in marine fishes - journal.pone.0083259.g001.png|thumb|Fluorescent marine fish]] [345] => Bony fishes living in shallow water generally have good color vision due to their living in a colorful environment. Thus, in shallow-water fishes, red, orange, and green fluorescence most likely serves as a means of communication with [[Biological specificity|conspecifics]], especially given the great phenotypic variance of the phenomenon. [346] => [347] => Many fish that exhibit fluorescence, such as [[sharks]], [[lizardfish]], [[scorpionfish]], [[wrasses]], and [[flatfishes]], also possess yellow intraocular filters.{{cite journal|last1=Heinermann|first1=P|title=Yellow intraocular filters in fishes|journal=Experimental Biology|date=2014-03-10|volume=43|issue=2|pages=127–147|pmid=6398222}} Yellow intraocular filters in the [[lens (anatomy)|lenses]] and [[cornea]] of certain fishes function as long-pass filters. These filters enable the species to visualize and potentially exploit fluorescence, in order to enhance visual contrast and patterns that are unseen to other fishes and predators that lack this visual specialization. Fish that possess the necessary yellow intraocular filters for visualizing fluorescence potentially exploit a light signal from members of it. Fluorescent patterning was especially prominent in cryptically patterned fishes possessing complex camouflage. Many of these lineages also possess yellow long-pass intraocular filters that could enable visualization of such patterns. [348] => [349] => Another adaptive use of fluorescence is to generate orange and red light from the ambient blue light of the [[photic zone]] to aid vision. Red light can only be seen across short distances due to attenuation of red light wavelengths by water.{{Cite journal | doi = 10.1186/1472-6785-8-16| pmid = 18796150| pmc = 2567963| title = Red fluorescence in reef fish: A novel signalling mechanism?| journal = BMC Ecology| volume = 8| page = 16| year = 2008| last1 = Michiels | first1 = N. K. | last2 = Anthes | first2 = N. | last3 = Hart | first3 = N. S. | last4 = Herler | first4 = J. R. | last5 = Meixner | first5 = A. J. | last6 = Schleifenbaum | first6 = F. | last7 = Schulte | first7 = G. | last8 = Siebeck | first8 = U. E. | last9 = Sprenger | first9 = D. | last10 = Wucherer | first10 = M. F. | issue = 1| doi-access = free| bibcode = 2008BMCE....8...16M}} Many fish species that fluoresce are small, group-living, or benthic/aphotic, and have conspicuous patterning. This patterning is caused by fluorescent tissue and is visible to other members of the species, however the patterning is invisible at other visual spectra. These intraspecific fluorescent patterns also coincide with intra-species signaling. The patterns present in ocular rings to indicate directionality of an individual's gaze, and along fins to indicate directionality of an individual's movement. Current research suspects that this red fluorescence is used for private communication between members of the same species.{{Cite journal | doi = 10.1371/journal.pone.0037913| pmid = 22701587| title = A Fluorescent Chromatophore Changes the Level of Fluorescence in a Reef Fish| journal = PLOS ONE| volume = 7| issue = 6| pages = e37913| year = 2012| last1 = Wucherer | first1 = M. F. | last2 = Michiels | first2 = N. K. |bibcode = 2012PLoSO...737913W | pmc=3368913| doi-access = free}} Due to the prominence of blue light at ocean depths, red light and light of longer wavelengths are muddled, and many predatory reef fish have little to no sensitivity for light at these wavelengths. Fish such as the fairy wrasse that have developed visual sensitivity to longer wavelengths are able to display red fluorescent signals that give a high contrast to the blue environment and are conspicuous to conspecifics in short ranges, yet are relatively invisible to other common fish that have reduced sensitivities to long wavelengths. Thus, fluorescence can be used as adaptive signaling and intra-species communication in reef fish. [350] => {{cite journal [351] => | pmid = 24870049 [352] => | pmc = 4071555 [353] => | year = 2014 [354] => | last1 = Gerlach [355] => | first1 = T [356] => | title = Fairy wrasses perceive and respond to their deep red fluorescent coloration [357] => | journal = Proceedings of the Royal Society B: Biological Sciences [358] => | volume = 281 [359] => | issue = 1787 [360] => | page = 20140787 [361] => | last2 = Sprenger [362] => | first2 = D [363] => | last3 = Michiels [364] => | first3 = N. K. [365] => | doi = 10.1098/rspb.2014.0787 [366] => }} [367] => [368] => Additionally, it is suggested that fluorescent [[tissue (biology)|tissues]] that surround an organism's eyes are used to convert blue light from the photic zone or green bioluminescence in the aphotic zone into red light to aid vision. [369] => [370] => ===== Sharks ===== [371] => A new [[fluorophore]] was described in two species of sharks, wherein it was due to an undescribed group of brominated tryptophane-kynurenine small molecule metabolites.{{Cite journal|last1=Park|first1=Hyun Bong|last2=Lam|first2=Yick Chong|last3=Gaffney|first3=Jean P.|last4=Weaver|first4=James C.|last5=Krivoshik|first5=Sara Rose|last6=Hamchand|first6=Randy|last7=Pieribone|first7=Vincent|last8=Gruber|first8=David F.|last9=Crawford|first9=Jason M.|date=2019-09-27|title=Bright Green Biofluorescence in Sharks Derives from Bromo-Kynurenine Metabolism|url= |journal=iScience|language=en|volume=19|pages=1291–1336|doi=10.1016/j.isci.2019.07.019|issn=2589-0042|pmid=31402257|pmc=6831821|bibcode=2019iSci...19.1291P}} [372] => [373] => ===== Coral ===== [374] => Fluorescence serves a wide variety of functions in coral. Fluorescent proteins in corals may contribute to photosynthesis by converting otherwise unusable wavelengths of light into ones for which the coral's symbiotic algae are able to conduct [[photosynthesis]].{{Cite journal | doi = 10.1038/35048564 | pmid = 11130722 | title = Fluorescent pigments in corals are photoprotective | year = 2000 | last1 = Salih | first1 = A. | journal = Nature | volume = 408 | issue = 6814 | pages = 850–3 | last2 = Larkum | first2 = A. | last3 = Cox | first3 = G. | last4 = Kühl | first4 = M. | last5 = Hoegh-Guldberg | first5 = O. | url = https://www.researchgate.net/publication/12197663 | bibcode = 2000Natur.408..850S | s2cid = 4300578 | url-status = live | archive-url = https://web.archive.org/web/20151222103614/https://www.researchgate.net/publication/12197663_Fluorescent_Pigments_in_Corals_are_Photoprotective | archive-date = 22 December 2015}} Also, the proteins may fluctuate in number as more or less light becomes available as a means of photoacclimation.{{Cite journal | doi = 10.1242/jeb.040881| title = Green fluorescent protein regulation in the coral Acropora yongei during photoacclimation| journal = Journal of Experimental Biology| volume = 213| issue = 21| pages = 3644–3655| year = 2010| last1 = Roth | first1 = M. S.| last2 = Latz | first2 = M. I.| last3 = Goericke | first3 = R.| last4 = Deheyn | first4 = D. D. | pmid=20952612| doi-access = free}} Similarly, these fluorescent proteins may possess antioxidant capacities to eliminate oxygen radicals produced by photosynthesis.{{Cite journal | doi = 10.1016/j.bbagen.2006.08.014| title = Quenching of superoxide radicals by green fluorescent protein| journal = Biochimica et Biophysica Acta (BBA) - General Subjects| volume = 1760| issue = 11| pages = 1690–1695| year = 2006| last1 = Bou-Abdallah | first1 = F. | last2 = Chasteen | first2 = N. D. | last3 = Lesser | first3 = M. P. | pmid=17023114 | pmc=1764454}} Finally, through modulating photosynthesis, the fluorescent proteins may also serve as a means of regulating the activity of the coral's photosynthetic algal symbionts.{{Cite journal | doi = 10.1007/s00239-005-0129-9| title = Adaptive Evolution of Multicolored Fluorescent Proteins in Reef-Building Corals| journal = Journal of Molecular Evolution| volume = 62| issue = 3| pages = 332–339| year = 2006| last1 = Field | first1 = S. F. | last2 = Bulina | first2 = M. Y. | last3 = Kelmanson | first3 = I. V. | last4 = Bielawski | first4 = J. P. | last5 = Matz | first5 = M. V. | pmid=16474984| bibcode = 2006JMolE..62..332F| s2cid = 12081922}} [375] => [376] => ===== Cephalopods ===== [377] => {{main|Cephalopods}} [378] => ''Alloteuthis subulata'' and ''Loligo vulgaris'', two types of nearly transparent squid, have fluorescent spots above their eyes. These spots reflect incident light, which may serve as a means of camouflage, but also for signaling to other squids for schooling purposes. [379] => {{cite journal [380] => |pmid = 11441052 [381] => |url = http://jeb.biologists.org/content/204/12/2103.short [382] => |year = 2001 [383] => |last1 = Mäthger [384] => |first1 = L. M. [385] => |title = Reflective properties of iridophores and fluorescent 'eyespots' in the loliginid squid ''Alloteuthis subulata'' and ''Loligo vulgaris'' [386] => |journal = The Journal of Experimental Biology [387] => |volume = 204 [388] => |issue = Pt 12 [389] => |pages = 2103–18 [390] => |last2 = Denton [391] => |first2 = E. J. [392] => |doi = 10.1242/jeb.204.12.2103 [393] => |author-link2 = Eric James Denton [394] => |url-status = live [395] => |archive-url = https://web.archive.org/web/20160304110727/http://jeb.biologists.org/content/204/12/2103.short [396] => |archive-date = 4 March 2016 [397] => }} [398] => [399] => ===== Jellyfish ===== [400] => [[File:Crystal Jelly ("Aequorea Victoria"), Monterey Bay Aquarium, Monterey, California, USA.jpg|thumb|''Aequoria victoria'', biofluorescent jellyfish known for GFP]] [401] => Another, well-studied example of fluorescence in the ocean is the [[hydrozoan]] ''[[Aequorea victoria]]''. This jellyfish lives in the photic zone off the west coast of North America and was identified as a carrier of [[green fluorescent protein]] (GFP) by [[Osamu Shimomura]]. The gene for these green fluorescent proteins has been isolated and is scientifically significant because it is widely used in genetic studies to indicate the expression of other genes.{{Cite journal | doi = 10.1146/annurev.biochem.67.1.509| title = The Green Fluorescent Protein| journal = Annual Review of Biochemistry| volume = 67| pages = 509–544| year = 1998| last1 = Tsien | first1 = R. Y.| s2cid = 8138960| pmid=9759496}} [402] => [403] => ===== Mantis shrimp ===== [404] => Several species of [[mantis shrimp]], which are stomatopod [[crustaceans]], including ''Lysiosquillina glabriuscula'', have yellow fluorescent markings along their antennal scales and [[carapace]] (shell) that males present during threat displays to predators and other males. The display involves raising the head and thorax, spreading the striking appendages and other maxillipeds, and extending the prominent, oval antennal scales laterally, which makes the animal appear larger and accentuates its yellow fluorescent markings. Furthermore, as depth increases, mantis shrimp fluorescence accounts for a greater part of the visible light available. During mating rituals, mantis shrimp actively fluoresce, and the wavelength of this fluorescence matches the wavelengths detected by their eye pigments.{{Cite journal | doi = 10.1126/science.1089803| title = Fluorescent Enhancement of Signaling in a Mantis Shrimp| journal = Science| volume = 303| issue = 5654| page = 51| year = 2004| last1 = Mazel | first1 = C. H.| s2cid = 35009047| pmid=14615546| doi-access = free}} [405] => [406] => ==== Aphotic zone ==== [407] => {{main|Aphotic zone}} [408] => [409] => ===== Siphonophores ===== [410] => ''[[Siphonophorae]]'' is an order of marine animals from the phylum [[Hydrozoa]] that consist of a specialized [[jellyfish|medusoid]] and [[polyp (zoology)|polyp]] [[zooid]]. Some siphonophores, including the genus Erenna that live in the aphotic zone between depths of 1600 m and 2300 m, exhibit yellow to red fluorescence in the [[photophores]] of their tentacle-like [[tentilla]]. This fluorescence occurs as a by-product of bioluminescence from these same photophores. The siphonophores exhibit the fluorescence in a flicking pattern that is used as a lure to attract prey. [411] => {{cite journal [412] => | doi = 10.1016/j.bbagen.2006.08.014 [413] => | title = Quenching of superoxide radicals by green fluorescent protein [414] => | journal = Biochimica et Biophysica Acta (BBA) - General Subjects [415] => | volume = 1760 [416] => | issue = 11 [417] => | pages = 1690–1695 [418] => | year = 2006 [419] => | last1 = Bou-Abdallah | first1 = F. [420] => | last2 = Chasteen | first2 = N. D. [421] => | last3 = Lesser | first3 = M. P. [422] => | pmid=17023114 [423] => | pmc=1764454 [424] => }} [425] => [426] => ===== Dragonfish ===== [427] => The predatory deep-sea [[Barbeled dragonfish|dragonfish]] ''Malacosteus niger'', the closely related genus ''[[Aristostomias]]'' and the species ''[[Pachystomias microdon]]'' use fluorescent red accessory pigments to convert the blue light emitted from their own bioluminescence to red light from suborbital [[photophores]]. This red luminescence is invisible to other animals, which allows these dragonfish extra light at dark ocean depths without attracting or signaling predators.{{Cite journal | doi = 10.1038/30871|title=Dragon fish see using chlorophyll|bibcode=1998Natur.393..423D| year = 1998| last1 = Douglas | first1 = R. H.| journal = Nature| volume = 393| issue = 6684| pages = 423–424| last2 = Partridge | first2 = J. C.| last3 = Dulai | first3 = K.| last4 = Hunt | first4 = D.| last5 = Mullineaux | first5 = C. W.| last6 = Tauber | first6 = A. Y.| last7 = Hynninen | first7 = P. H.|s2cid=4416089}} [428] => [429] => === Terrestrial === [430] => ==== Amphibians ==== [431] => [[File:Hypsiboas punctatus fluorescente.jpg|thumb|Fluorescent [[polka-dot tree frog]] under UV-light]] [432] => [433] => Fluorescence is widespread among [[amphibian]]s and has been documented in several families of [[frog]]s, [[salamander]]s and [[caecilian]]s, but the extent of it varies greatly.{{cite journal | author1=Lamb, J.Y. | author2=M.P. Davis | year=2020 | title=Salamanders and other amphibians are aglow with biofluorescence | journal=Scientific Reports | volume=10 | issue=1 | page=2821 | doi=10.1038/s41598-020-59528-9 | pmid=32108141 | pmc=7046780 | bibcode=2020NatSR..10.2821L }} [434] => [435] => The [[polka-dot tree frog]] (''Hypsiboas punctatus''), widely found in South America, was unintentionally discovered to be the first fluorescent amphibian in 2017. The fluorescence was traced to a new compound found in the [[lymph]] and skin glands.{{cite news |last=Wong |first=Sam |date=13 March 2017 |title=Luminous frog is the first known naturally fluorescent amphibian |url=https://www.newscientist.com/article/2124466-luminous-frog-is-the-first-known-naturally-fluorescent-amphibian/ |access-date=2017-03-22 |url-status=live |archive-url=https://web.archive.org/web/20170320143233/https://www.newscientist.com/article/2124466-luminous-frog-is-the-first-known-naturally-fluorescent-amphibian/ |archive-date=20 March 2017}} The main fluorescent compound is Hyloin-L1 and it gives a blue-green glow when exposed to violet or [[ultraviolet light]]. The scientists behind the discovery suggested that the fluorescence can be used for communication. They speculated that fluorescence possibly is relatively widespread among frogs.{{cite news |last=King |first=Anthony |date=13 March 2017 |title=Fluorescent frog first down to new molecule |url=https://www.chemistryworld.com/news/fluorescent-frog-first-down-to-new-molecule-/2500541.article |access-date=2017-03-22 |url-status=live |archive-url=https://web.archive.org/web/20170322191916/https://www.chemistryworld.com/news/fluorescent-frog-first-down-to-new-molecule-/2500541.article |archive-date=22 March 2017}} Only a few months later, fluorescence was discovered in the closely related ''[[Hypsiboas atlanticus]]''. Because it is linked to secretions from skin glands, they can also leave fluorescent markings on surfaces where they have been.{{cite journal | author1=Taboada, C. | author2=A.E. Brunetti | author3=C. Alexandre | author4=M.G. Lagorio | author5=J. Faivovich | year=2017 | title=Fluorescent Frogs: A Herpetological Perspective | journal=South American Journal of Herpetology | volume=12 | issue=1 | pages=1–13 | doi=10.2994/SAJH-D-17-00029.1 | s2cid=89815080 }} [436] => [437] => In 2019, two other frogs, the tiny [[pumpkin toadlet]] (''Brachycephalus ephippium'') and [[red pumpkin toadlet]] (''B. pitanga'') of southeastern Brazil, were found to have naturally fluorescent skeletons, which are visible through their skin when exposed to ultraviolet light.{{cite journal | author1=Sandra Goutte | author2=Matthew J. Mason | author3=Marta M. Antoniazzi | author4=Carlos Jared | author5=Didier Merle | author6=Lilian Cazes | author7=Luís Felipe Toledo | author8=Hanane el-Hafci | author9=Stéphane Pallu | author10=Hugues Portier | author11=Stefan Schramm | author12=Pierre Gueriau | author13=Mathieu Thoury | year=2019 | title=Intense bone fluorescence reveals hidden patterns in pumpkin toadlets | journal=Scientific Reports | volume=9 | issue=1 | page=5388 | doi=10.1038/s41598-019-41959-8 | pmid=30926879 | pmc=6441030 | bibcode=2019NatSR...9.5388G }}{{cite web | author=Fox, A. | title=Scientists discover a frog with glowing bones | url=https://www.science.org/content/article/scientists-discover-frog-glowing-bones | date=2 April 2019 | website=ScienceMag | access-date=9 February 2020 | archive-date=8 March 2020 | archive-url=https://web.archive.org/web/20200308114612/https://www.sciencemag.org/news/2019/04/scientists-discover-frog-glowing-bones | url-status=live }} It was initially speculated that the fluorescence supplemented their already [[aposematic]] colours (they are toxic) or that it was related to [[mate choice]] ([[species recognition]] or determining fitness of a potential partner), but later studies indicate that the former explanation is unlikely, as predation attempts on the toadlets appear to be unaffected by the presence/absence of fluorescence.{{cite journal | author1=Rebouças, R. | author2=A.B. Carollo | author3=M.d.O. Freitas | author4=C. Lambertini | author5=R.M. Nogueira dos Santos | author6=L.F. Toledo | year=2019 | title= Conservation Status of Brachycephalus Toadlets (Anura: Brachycephalidae) from the Brazilian Atlantic Rainforest| journal= Diversity| volume=55 | issue=1 | pages=39–47 | doi=10.3390/d11090150 | doi-access=free }} [438] => [439] => In 2020 it was confirmed that green or yellow fluorescence is widespread not only in adult frogs that are exposed to blue or ultraviolet light, but also among [[tadpole]]s, salamanders and caecilians. The extent varies greatly depending on species; in some it is highly distinct and in others it is barely noticeable. It can be based on their skin pigmentation, their mucous or their bones. [440] => [441] => ==== Butterflies ==== [442] => [[swallowtail butterfly|Swallowtail]] (''Papilio'') butterflies have complex systems for emitting fluorescent light. Their wings contain pigment-infused crystals that provide directed fluorescent light. These crystals function to produce fluorescent light best when they absorb [[radiance]] from sky-blue light (wavelength about 420 nm). The wavelengths of light that the butterflies see the best correspond to the absorbance of the crystals in the butterfly's wings. This likely functions to enhance the capacity for signaling. [443] => {{cite journal [444] => | pmid = 16293753 [445] => | year = 2005 [446] => | last1 = Vukusic [447] => | first1 = P [448] => | title = Directionally controlled fluorescence emission in butterflies [449] => | journal = Science [450] => | volume = 310 [451] => | issue = 5751 [452] => | page = 1151 [453] => | last2 = Hooper [454] => | first2 = I [455] => | s2cid = 43857104 [456] => | doi = 10.1126/science.1116612 [457] => }} [458] => [459] => ==== Parrots ==== [460] => [[Parrots]] have fluorescent [[plumage]] that may be used in mate signaling. A study using mate-choice experiments on [[budgerigars]] (''Melopsittacus undulates'') found compelling support for fluorescent sexual signaling, with both males and females significantly preferring birds with the fluorescent experimental stimulus. This study suggests that the fluorescent plumage of parrots is not simply a by-product of [[pigmentation]], but instead an adapted sexual signal. Considering the intricacies of the pathways that produce fluorescent pigments, there may be significant costs involved. Therefore, individuals exhibiting strong fluorescence may be honest indicators of high individual quality, since they can deal with the associated costs.{{Cite journal| doi = 10.1126/science.295.5552.92| pmid = 11778040| title = Fluorescent Signaling in Parrots| journal = Science| volume = 295| issue = 5552| page = 92| year = 2002| last1 = Arnold| first1 = K. E.| citeseerx = 10.1.1.599.1127}} [461] => [462] => ==== Arachnids ==== [463] => [[File:Sorpion Under Blacklight edit.jpg|thumb|Fluorescing scorpion]] [464] => Spiders fluoresce under UV light and possess a huge diversity of fluorophores. Andrews, Reed, & Masta noted that spiders are the only known group in which fluorescence is "taxonomically widespread, variably expressed, evolutionarily labile, and probably under selection and potentially of ecological importance for intraspecific and interspecific signaling". They showed that fluorescence evolved multiple times across spider taxa, with novel fluorophores evolving during spider diversification. [465] => [466] => In some spiders, ultraviolet cues are important for predator–prey interactions, intraspecific communication, and camouflage-matching with fluorescent flowers. Differing ecological contexts could favor inhibition or enhancement of fluorescence expression, depending upon whether fluorescence helps spiders be cryptic or makes them more conspicuous to predators. Therefore, natural selection could be acting on expression of fluorescence across spider species. [467] => {{cite journal [468] => | last1 = Andrews | first1 = K. [469] => | last2 = Reed | first2 = S.M. [470] => | last3 = Masta | first3 = S.E. [471] => | year = 2007 [472] => | title = Spiders fluoresce variably across many taxa [473] => | journal = Biology Letters [474] => | volume = 3 | issue = 3 | pages = 265–267 [475] => | doi = 10.1098/rsbl.2007.0016 [476] => | pmid = 17412670 | pmc = 2104643 [477] => }} [478] => [479] => Scorpions are also fluorescent, in their case due to the presence of [[beta carboline]] in their cuticles. [480] => {{cite journal [481] => | last1 = Stachel | first1 = S.J. [482] => | last2 = Stockwell | first2 = S.A. [483] => | last3 = van Vranken | first3 = D.L. [484] => | year = 1999 [485] => | title = The fluorescence of scorpions and cataractogenesis [486] => | journal = Chemistry & Biology [487] => | volume = 6 | issue = 8 | pages = 531–539 [488] => | doi = 10.1016/S1074-5521(99)80085-4 [489] => | doi-access = free | pmid=10421760 [490] => }} [491] => [492] => [493] => ==== Platypus ==== [494] => In 2020 fluorescence was reported for several [[platypus]] specimens. [495] => {{cite journal [496] => | last = Spaeth | first = P. [497] => | year = 2020 [498] => | title = Biofluorescence in the platypus (Ornithorhynchus anatinus) [499] => | journal = Mammalia [500] => | volume = 85 | issue = 2 | pages = 179–181 [501] => | doi = 10.1515/mammalia-2020-0027 [502] => | doi-access = free [503] => }} [504] => [505] => ==== Plants ==== [506] => Many plants are fluorescent due to the presence of [[chlorophyll]], which is probably the most widely distributed fluorescent molecule, producing red emission under a range of excitation wavelengths.{{Cite book|url=https://books.google.com/books?id=x2PZRC6Zd5sC&q=Chlorophyll+fluoresces+a+weak+red+under+ultraviolet+light.&pg=PA12|title=Photobiology of Higher Plants|last=McDonald|first=Maurice S.|date=2003-06-02|publisher=John Wiley & Sons|isbn=9780470855232|language=en|url-status=live|archive-url=https://web.archive.org/web/20171221200631/https://books.google.com/books?id=x2PZRC6Zd5sC&pg=PA12&dq=Chlorophyll+fluoresces+a+weak+red+under+ultraviolet+light.&hl=en&sa=X&ved=0ahUKEwiRlYCz85vYAhWJgVQKHZhsDrYQ6AEIODAD#v=onepage&q=Chlorophyll%20fluoresces%20a%20weak%20red%20under%20ultraviolet%20light.&f=false|archive-date=21 December 2017}} This attribute of chlorophyll is commonly used by ecologists to measure photosynthetic efficiency.{{Cite web|url=https://climexhandbook.w.uib.no/2019/11/03/chlorophyll-fluorescence/|title=5.1 Chlorophyll fluorescence – ClimEx Handbook|language=en-US|access-date=2020-01-14|archive-date=14 January 2020|archive-url=https://web.archive.org/web/20200114153538/https://climexhandbook.w.uib.no/2019/11/03/chlorophyll-fluorescence/|url-status=live}} [507] => [508] => The ''Mirabilis jalapa'' flower contains violet, fluorescent betacyanins and yellow, fluorescent betaxanthins. Under white light, parts of the flower containing only betaxanthins appear yellow, but in areas where both betaxanthins and betacyanins are present, the visible fluorescence of the flower is faded due to internal light-filtering mechanisms. Fluorescence was previously suggested to play a role in [[pollinator]] attraction, however, it was later found that the visual signal by fluorescence is negligible compared to the visual signal of light reflected by the flower.{{Cite journal | doi = 10.1007/s00114-010-0709-4| title = Is the flower fluorescence relevant in biocommunication?| journal = Naturwissenschaften| volume = 97| issue = 10| pages = 915–924| year = 2010| last1 = Iriel | first1 = A. A. | last2 = Lagorio | first2 = M. A. G. |bibcode = 2010NW.....97..915I | pmid=20811871| s2cid = 43503960}} [509] => [510] => === Abiotic === [511] => ==== Gemology, mineralogy and geology ==== [512] => [[File:Aragonit - Fluorescence.gif|thumb|left|Fluorescence of [[aragonite]]]] [513] => [[File:Rough diamonds - necklace in UV and normal light B - composite.jpg|thumb|left|Necklace of rough diamonds under [[Blacklight|UV light]] (top) and normal light (bottom)]] [514] => In addition to the eponyous [[fluorspar]],Raman, C.V., (1962). [https://www.currentscience.ac.in/Volumes/31/09/0361.pdf "The luminescence of fluorspar"], Curr. Sci., 31, 361–365 many [515] => [[gemstone]]s and [[mineral]]s may have a distinctive fluorescence or may fluoresce differently under short-wave ultraviolet, long-wave ultraviolet, visible light, or [[X-ray]]s. [516] => [517] => Many types of [[calcite]] and [[amber]] will fluoresce under shortwave UV, longwave UV and visible light. [[Ruby|Rubies]], [[emerald]]s, and [[diamond]]s exhibit red fluorescence under long-wave UV, blue and sometimes green light; diamonds also emit light under [[X-ray]] radiation. [518] => [519] => Fluorescence in minerals is caused by a wide range of [[Activator (phosphor)|activators]]. In some cases, the concentration of the activator must be restricted to below a certain level, to prevent quenching of the fluorescent emission. Furthermore, the mineral must be free of impurities such as [[iron]] or [[copper]], to prevent quenching of possible fluorescence. Divalent [[manganese]], in concentrations of up to several percent, is responsible for the red or orange fluorescence of [[calcite]], the green fluorescence of [[willemite]], the yellow fluorescence of [[esperite]], and the orange fluorescence of [[wollastonite]] and [[clinohedrite]]. Hexavalent [[uranium]], in the form of the [[uranyl cation]] ({{chem|UO|2|2+}}), fluoresces at all concentrations in a yellow green, and is the cause of fluorescence of minerals such as [[autunite]] or [[andersonite]], and, at low concentration, is the cause of the fluorescence of such materials as some samples of [[hyalite]] [[opal]]. Trivalent [[chromium]] at low concentration is the source of the red fluorescence of [[ruby]]. Divalent [[europium]] is the source of the blue fluorescence, when seen in the mineral [[fluorite]]. Trivalent [[lanthanide]]s such as [[terbium]] and [[dysprosium]] are the principal activators of the creamy yellow fluorescence exhibited by the [[yttrofluorite]] variety of the mineral fluorite, and contribute to the orange fluorescence of [[zircon]]. [[Powellite]] ([[calcium molybdate]]) and [[scheelite]] (calcium tungstate) fluoresce intrinsically in yellow and blue, respectively. When present together in [[solid solution]], energy is transferred from the higher-energy [[tungsten]] to the lower-energy [[molybdenum]], such that fairly low levels of [[molybdenum]] are sufficient to cause a yellow emission for [[scheelite]], instead of blue. Low-iron [[sphalerite]] (zinc sulfide), fluoresces and phosphoresces in a range of colors, influenced by the presence of various trace impurities. [520] => [521] => Crude oil ([[petroleum]]) fluoresces in a range of colors, from dull-brown for heavy oils and tars through to bright-yellowish and bluish-white for very light oils and condensates. This phenomenon is used in [[oil exploration]] drilling to identify very small amounts of oil in drill cuttings and core samples. [522] => [523] => [[Humic acid]]s and [[fulvic acid]]s produced by the degradation of [[organic matter]] in soils ([[humus]]) may also fluoresce because of the presence of aromatic cycles in their complex [[molecular structure]]s.{{Cite journal| doi = 10.1021/es960132l| issn = 0013-936X| volume = 30| issue = 10| pages = 3061–3065| last1 = Mobed| first1 = Jarafshan J.| last2 = Hemmingsen| first2 = Sherry L.| last3 = Autry| first3 = Jennifer L.| last4 = McGown| first4 = Linda B.| title = Fluorescence characterization of IHSS humic substances: Total luminescence spectra with absorbance correction| journal = Environmental Science & Technology| accessdate = 2021-08-29| date = 1996-09-01| bibcode = 1996EnST...30.3061M| url = https://doi.org/10.1021/es960132l| archive-date = 4 May 2022| archive-url = https://web.archive.org/web/20220504144922/https://pubs.acs.org/doi/10.1021/es960132l| url-status = live}} Humic substances dissolved in [[groundwater]] can be detected and characterized by [[spectrofluorimetry]].{{Cite journal| issn = 0038-075X| volume = 167| issue = 11| pages = 739–749| last1 = Milori| first1 = Débora MBP| last2 = Martin-Neto| first2 = Ladislau| last3 = Bayer| first3 = Cimélio| last4 = Mielniczuk| first4 = João| last5 = Bagnato| first5 = Vanderlei S| title = Humification degree of soil humic acids determined by fluorescence spectroscopy| journal = Soil Science| date = 2002| doi = 10.1097/00010694-200211000-00004| bibcode = 2002SoilS.167..739M| s2cid = 98552138}} [524] => {{Cite journal| issn = 0013-936X| volume = 38| issue = 7| pages = 2052–2057| last1 = Richard| first1 = C| last2 = Trubetskaya| first2 = O| last3 = Trubetskoj| first3 = O| last4 = Reznikova| first4 = O| last5 = Afanas' Eva| first5 = G| last6 = Aguer| first6 = J-P| last7 = Guyot| first7 = G| title = Key role of the low molecular size fraction of soil humic acids for fluorescence and photoinductive activity| journal = Environmental Science & Technology| date = 2004| doi = 10.1021/es030049f| pmid = 15112806| bibcode = 2004EnST...38.2052R}} [525] => {{Cite journal| issn = 0045-6535| volume = 58| issue = 6| pages = 715–733| last1 = Sierra| first1 = MMD| last2 = Giovanela| first2 = M| last3 = Parlanti| first3 = E| last4 = Soriano-Sierra| first4 = EJ| title = Fluorescence fingerprint of fulvic and humic acids from varied origins as viewed by single-scan and excitation/emission matrix techniques| journal = Chemosphere| date = 2005| doi = 10.1016/j.chemosphere.2004.09.038| pmid = 15621185| bibcode = 2005Chmsp..58..715S}} [526] => [527] => ==== Organic liquids ==== [528] => [[File:Fluorescence in beer @ 450nm illumination.jpg|thumb|Organic molecules found naturally in beer, such as [[tryptophan]], [[tyrosine]], and [[phenylalanine]], fluoresce in green, ranging from 500 nm (light blue) to 600 nm (amber yellow) when illuminated with 450 nm (deep blue) laser light.[https://link.springer.com/article/10.1007/s10895-019-02421-0 The Parallel Factor Analysis of Beer Fluorescence by Tatjana Dramićanin, Ivana Zeković, Jovana Periša & Miroslav D. Dramićanin]]] [529] => Organic (carbon based) solutions such [[anthracene]] or [[stilbene]], dissolved in [[benzene]] or [[toluene]], fluoresce with [[ultraviolet]] or [[gamma ray]] [[irradiation]]. The decay times of this fluorescence are on the order of nanoseconds, since the duration of the light depends on the lifetime of the excited states of the fluorescent material, in this case anthracene or stilbene.{{Cite journal |doi = 10.1088/0370-1328/79/3/306|title = The Fluorescence and Scintillation Decay Times of Crystalline Anthracene|journal = Proceedings of the Physical Society|volume = 79|issue = 3|pages = 494–496|year = 1962|last1 = Birks|first1 = J. B.|s2cid = 17394465|bibcode = 1962PPS....79..494B}} [530] => [531] => [[Scintillation (physics)|Scintillation]] is defined a flash of light produced in a transparent material by the passage of a particle (an electron, an alpha particle, an ion, or a high-energy photon). Stilbene and derivatives are used in [[scintillation counter]]s to detect such particles. Stilbene is also one of the [[gain medium]]s used in [[dye lasers]]. [532] => [533] => ==== Atmosphere ==== [534] => Fluorescence is observed in the atmosphere when the air is under energetic electron bombardment. In cases such as the natural [[aurora]], high-altitude nuclear explosions, and rocket-borne electron gun experiments, the molecules and ions formed have a fluorescent response to light. [535] => {{Cite journal| doi = 10.1063/1.555910| title = Franck–Condon Factors, r-Centroids, Electronic Transition Moments, and Einstein Coefficients for Many Nitrogen and Oxygen Band Systems| journal = Journal of Physical and Chemical Reference Data| volume = 21| issue = 5| page = 1005| year = 1992| last1 = Gilmore| first1 = F. R.| last2 = Laher| first2 = R. R.| last3 = Espy| first3 = P. J.| bibcode = 1992JPCRD..21.1005G| url = https://apps.dtic.mil/sti/citations/ADA246065| url-status = live| archive-url = https://web.archive.org/web/20170709141516/http://www.dtic.mil/docs/citations/ADA246065| archive-date = 9 July 2017}} [536] => [537] => ==== Common materials that fluoresce ==== [538] => * [[Vitamin B2]] fluoresces yellow. [539] => * [[Tonic water]] fluoresces blue due to the presence of [[quinine]]. [540] => * [[Highlighter]] ink is often fluorescent due to the presence of [[pyranine]]. [541] => * [[Banknote]]s, [[postage stamp]]s and [[credit card]]s often have fluorescent security features. [542] => [543] => == In novel technology == [544] => In August 2020 researchers reported the creation of the brightest fluorescent solid optical materials so far by enabling the transfer of properties of highly fluorescent [[dye]]s via spatial and electronic isolation of the dyes by mixing cationic dyes with anion-binding [[cyanostar]] [[macrocycle]]s. According to a co-author these materials may have applications in areas such as solar energy harvesting, bioimaging, and lasers.{{cite news |title=Chemists create the brightest-ever fluorescent materials |url=https://phys.org/news/2020-08-chemists-brightest-ever-fluorescent-materials.html |access-date=6 September 2020 |work=phys.org |language=en |archive-date=3 September 2020 |archive-url=https://web.archive.org/web/20200903110237/https://phys.org/news/2020-08-chemists-brightest-ever-fluorescent-materials.html |url-status=live }}{{cite news |title=Scientists create the brightest fluorescent materials in existence |url=https://newatlas.com/materials/brightest-fluorescent-material-existence/ |access-date=6 September 2020 |work=New Atlas |date=7 August 2020 |archive-date=13 September 2020 |archive-url=https://web.archive.org/web/20200913070357/https://newatlas.com/materials/brightest-fluorescent-material-existence/ |url-status=live }}{{cite news |title=Scientists create 'brightest known materials in existence' |url=https://www.independent.co.uk/life-style/gadgets-and-tech/news/brightest-material-ever-fluorescent-light-a9657221.html |access-date=6 September 2020 |work=independent.co.uk |language=en |archive-date=25 September 2020 |archive-url=https://web.archive.org/web/20200925152324/https://www.independent.co.uk/life-style/gadgets-and-tech/news/brightest-material-ever-fluorescent-light-a9657221.html |url-status=live }}{{cite journal |last1=Benson |first1=Christopher R. |last2=Kacenauskaite |first2=Laura |last3=VanDenburgh |first3=Katherine L. |last4=Zhao |first4=Wei |last5=Qiao |first5=Bo |last6=Sadhukhan |first6=Tumpa |last7=Pink |first7=Maren |last8=Chen |first8=Junsheng |last9=Borgi |first9=Sina |last10=Chen |first10=Chun-Hsing |last11=Davis |first11=Brad J. |last12=Simon |first12=Yoan C. |last13=Raghavachari |first13=Krishnan |last14=Laursen |first14=Bo W. |last15=Flood |first15=Amar H. |title=Plug-and-Play Optical Materials from Fluorescent Dyes and Macrocycles |journal=Chem |date=6 August 2020 |volume=6 |issue=8 |pages=1978–1997 |doi=10.1016/j.chempr.2020.06.029 |language=en |issn=2451-9294|doi-access=free }} [545] => [546] => == Applications == [547] => === Lighting === [548] => {{further|Fluorescent lamp|Blacklight}} [549] => [[File:Art exhibition under black light.jpg|thumb|Fluorescent paint and plastic lit by UV-A lamps ([[blacklight]]). Paintings by Beo Beyond.]] [550] => [551] => The common [[fluorescent lamp]] relies on fluorescence. Inside the [[glass]] tube is a partial vacuum and a small amount of [[mercury (element)|mercury]]. An electric discharge in the tube causes the mercury atoms to emit mostly ultraviolet light. The tube is lined with a coating of a fluorescent material, called the ''[[phosphor]]'', which absorbs ultraviolet light and re-emits visible light. Fluorescent [[lighting]] is more energy-efficient than [[incandescent]] lighting elements. However, the uneven [[spectrum]] of traditional fluorescent lamps may cause certain colors to appear different from when illuminated by incandescent light or [[daylight]]. The mercury vapor emission spectrum is dominated by a short-wave UV line at 254 nm (which provides most of the energy to the phosphors), accompanied by visible light emission at 436 nm (blue), 546 nm (green) and 579 nm (yellow-orange). These three lines can be observed superimposed on the white continuum using a hand spectroscope, for light emitted by the usual white fluorescent tubes. These same visible lines, accompanied by the emission lines of trivalent europium and trivalent terbium, and further accompanied by the emission continuum of divalent europium in the blue region, comprise the more discontinuous light emission of the modern trichromatic phosphor systems used in many [[compact fluorescent lamp]] and traditional lamps where better color rendition is a goal.{{cite web|last=Harris|first=Tom|title=How Fluorescent Lamps Work|url=http://home.howstuffworks.com/fluorescent-lamp.htm|work=HowStuffWorks|publisher=Discovery Communications|access-date=27 June 2010|url-status=live|archive-url=https://web.archive.org/web/20100706040948/http://home.howstuffworks.com/fluorescent-lamp.htm|archive-date=6 July 2010|date=2001-12-07}} [552] => [553] => Fluorescent lights were first available to the public at the [[1939 New York World's Fair]]. Improvements since then have largely been better phosphors, longer life, and more consistent internal discharge, and easier-to-use shapes (such as compact fluorescent lamps). Some [[High-intensity discharge lamp|high-intensity discharge (HID) lamps]] couple their even-greater electrical efficiency with phosphor enhancement for better color rendition.{{Cite book |last=Flesch |first=P. |url=https://www.worldcat.org/oclc/262693002 |title=Light and light sources: high-intensity discharge lamps |date=2006 |publisher=Springer-Verlag |isbn=978-3-540-32685-4 |location=Berlin |oclc=262693002}} [554] => [555] => White [[light-emitting diode]]s (LEDs) became available in the mid-1990s as [[LED lamp]]s, in which blue light emitted from the [[semiconductor]] strikes phosphors deposited on the tiny chip. The combination of the blue light that continues through the phosphor and the green to red fluorescence from the phosphors produces a net emission of white light.{{Cite journal|last1=Chen|first1=Lei|last2=Lin|first2=Chun-Che|last3=Yeh|first3=Chiao-Wen|last4=Liu|first4=Ru-Shi|date=2010-03-22|title=Light Converting Inorganic Phosphors for White Light-Emitting Diodes|journal=Materials|volume=3|issue=3|pages=2172–2195|doi=10.3390/ma3032172|issn=1996-1944|pmc=5445896|bibcode=2010Mate....3.2172C|doi-access=free}} [556] => [557] => [[Glow stick]]s sometimes utilize fluorescent materials to absorb light from the [[chemiluminescence|chemiluminescent]] reaction and emit light of a different color. [558] => [559] => === Analytical chemistry === [560] => Many analytical procedures involve the use of a [[fluorometer]], usually with a single exciting wavelength and single detection wavelength. Because of the sensitivity that the method affords, fluorescent molecule concentrations as low as 1 part per trillion can be measured.{{Cite journal | doi = 10.1006/abio.1993.1020| title = Fluorometric Assay Using Dimeric Dyes for Double- and Single-Stranded DNA and RNA with Picogram Sensitivity| journal = Analytical Biochemistry| volume = 208| issue = 1| pages = 144–150| year = 1993| last1 = Rye | first1 = H. S. | last2 = Dabora | first2 = J. M. | last3 = Quesada | first3 = M. A. | last4 = Mathies | first4 = R. A. | last5 = Glazer | first5 = A. N. | pmid=7679561}} [561] => [562] => Fluorescence in several wavelengths can be detected by an [[Chromatography detector|array detector]], to detect compounds from [[High-performance liquid chromatography|HPLC]] flow. Also, [[Thin layer chromatography|TLC]] plates can be visualized if the compounds or a coloring reagent is fluorescent. Fluorescence is most effective when there is a larger ratio of atoms at lower energy levels in a [[Boltzmann distribution]]. There is, then, a higher probability of excitement and release of photons by lower-energy atoms, making analysis more efficient. [563] => [564] => === Spectroscopy === [565] => {{Main|Fluorescence spectroscopy}} [566] => Usually the setup of a fluorescence assay involves a light source, which may emit many different wavelengths of light. In general, a single wavelength is required for proper analysis, so, in order to selectively filter the light, it is passed through an excitation monochromator, and then that chosen wavelength is passed through the sample cell. After absorption and re-emission of the energy, many wavelengths may emerge due to [[Stokes shift]] and various [[electron transition]]s. To separate and analyze them, the fluorescent radiation is passed through an emission [[monochromator]], and observed selectively by a detector.{{cite book|author=Harris, Daniel C.|title=Exploring chemical analysis|url=https://books.google.com/books?id=x5eEW76lizEC|date=2004|publisher=Macmillan|isbn=978-0-7167-0571-0|url-status=live|archive-url=https://web.archive.org/web/20160731220213/https://books.google.com/books?id=x5eEW76lizEC|archive-date=31 July 2016}} [567] => [568] => === Lasers === [569] => [[File:Dye laser alignment intra-cavity beam @ 589nm.jpg|thumb|The internal cavity of a dye laser tuned to 589 nm. The green beam from a frequency-doubled [[Nd:YAG laser]] causes the dye solution to fluoresce in yellow, creating a beam between the array of mirrors.]] [570] => [[Laser]]s most often use the fluorescence of certain materials as their active media, such as the red glow produced by a [[ruby laser|ruby]] (chromium sapphire), the infrared of [[titanium-sapphire laser|titanium sapphire]], or the unlimited range of colors produced by [[dye laser|organic dyes]]. These materials normally fluoresce through a process called [[spontaneous emission]], in which the light is emitted in all directions and often at many discrete spectral lines all at once. In many lasers, the fluorescent medium is [[laser pumping|"pumped"]] by exposing it to an intense light source, creating a [[population inversion]], meaning that more of its atoms become in an excited state (high energy) rather than at ground state (low energy). When this occurs, the spontaneous fluorescence can then induce the other atoms to emit their photons in the same direction and at the same wavelength, creating [[stimulated emission]]. When a portion of the spontaneous fluorescence is trapped between two mirrors, nearly all of the medium's fluorescence can be stimulated to emit along the same line, producing a laser beam.''Fundamental and Details of Laser Welding'' by Seiji Katayama – Springer 2020 p. 3–5 [571] => [572] => === Biochemistry and medicine === [573] => {{Main|Fluorescence in the life sciences}} [574] => [[Image:FluorescentCells.jpg|thumb|right|[[Endothelium|Endothelial cells]] under the microscope with three separate channels marking specific cellular components]] [575] => Fluorescence in the life sciences is used generally as a non-destructive way of tracking or analysis of biological molecules by means of the fluorescent emission at a specific frequency where there is no background from the excitation light, as relatively few cellular components are naturally fluorescent (called intrinsic or [[autofluorescence]]). [576] => In fact, a [[protein]] or other component can be "labelled" with an extrinsic [[fluorophore]], a fluorescent [[dye]] that can be a small molecule, protein, or quantum dot, finding a large use in many biological applications.{{rp|style=ama|p= {{mvar|xxvi}} }} [577] => [578] => The quantification of a dye is done with a [[spectrofluorometer]] and finds additional applications in: [579] => [580] => ==== Microscopy ==== [581] => * When scanning the fluorescence intensity across a plane one has [[fluorescence microscope|fluorescence microscopy]] of tissues, cells, or subcellular structures, which is accomplished by labeling an antibody with a fluorophore and allowing the antibody to find its target antigen within the sample. Labelling multiple antibodies with different fluorophores allows visualization of multiple targets within a single image (multiple channels). DNA microarrays are a variant of this. [582] => * Immunology: An antibody is first prepared by having a fluorescent chemical group attached, and the sites (e.g., on a microscopic specimen) where the antibody has bound can be seen, and even quantified, by the fluorescence. [583] => * FLIM ([[Fluorescence Lifetime Imaging Microscopy]]) can be used to detect certain bio-molecular interactions that manifest themselves by influencing fluorescence lifetimes. [584] => * Cell and molecular biology: detection of [[colocalization]] using fluorescence-labelled antibodies for selective detection of the antigens of interest using specialized software such as ImageJ. [585] => [586] => ==== Other techniques ==== [587] => * FRET ([[Förster resonance energy transfer]], also known as [[fluorescence resonance energy transfer]]) is used to study protein interactions, detect specific nucleic acid sequences and used as biosensors, while fluorescence lifetime (FLIM) can give an additional layer of information. [588] => * Biotechnology: [[biosensors]] using fluorescence are being studied as possible [[Fluorescent glucose biosensors]]. [589] => * Automated sequencing of [[DNA]] by the [[chain termination method]]; each of four different chain terminating bases has its own specific fluorescent tag. As the labelled DNA molecules are separated, the fluorescent label is excited by a UV source, and the identity of the base terminating the molecule is identified by the wavelength of the emitted light. [590] => * FACS ([[fluorescence-activated cell sorting]]). One of several important [[cell sorting]] techniques used in the separation of different cell lines (especially those isolated from animal tissues). [591] => * DNA detection: the compound [[ethidium bromide]], in aqueous solution, has very little fluorescence, as it is quenched by water. Ethidium bromide's fluorescence is greatly enhanced after it binds to DNA, so this compound is very useful in visualising the location of DNA fragments in [[agarose gel electrophoresis]]. Intercalated ethidium is in a hydrophobic environment when it is between the base pairs of the DNA, protected from quenching by water which is excluded from the local environment of the intercalated ethidium. Ethidium bromide may be carcinogenic – an arguably safer alternative is the dye [[SYBR Green]]. [592] => * FIGS ([[Fluorescence image-guided surgery]]) is a medical imaging technique that uses fluorescence to detect properly labeled structures during surgery. [593] => * [[Intravascular fluorescence]] is a catheter-based medical imaging technique that uses fluorescence to detect high-risk features of atherosclerosis and unhealed vascular stent devices.{{cite journal|author-link3=Vasi;is Ntziachristos|vauthors=Calfon MA, Vinegoni C, Ntziachristos V, Jaffer FA | title=Intravascular near-infrared fluorescence molecular imaging of atherosclerosis: toward coronary arterial visualization of biologically high-risk plaques. | journal=J Biomed Opt | year= 2010 | volume= 15 | issue= 1 | pages= 011107–011107–6 | pmid=20210433 | doi=10.1117/1.3280282 | pmc=3188610 | bibcode=2010JBO....15a1107C }} Plaque autofluorescence has been used in a first-in-man study in coronary arteries in combination with [[optical coherence tomography]].{{cite journal|vauthors=Ughi GJ, Wang H, Gerbaud E, Gardecki JA, Fard AM, Hamidi E, etal |title=Clinical Characterization of Coronary Atherosclerosis With Dual-Modality OCT and Near-Infrared Autofluorescence Imaging | journal=JACC Cardiovasc Imaging | year= 2016 | volume= 9| issue= 11| pages= 1304–1314| pmid=26971006 | pmc=5010789 | doi=10.1016/j.jcmg.2015.11.020}} Molecular agents has been also used to detect specific features, such as stent [[fibrin]] accumulation and enzymatic activity related to artery inflammation.{{cite journal|vauthors=Hara T, Ughi GJ, McCarthy JR, Erdem SS, Mauskapf A, Lyon SC, etal | title=Intravascular fibrin molecular imaging improves the detection of unhealed stents assessed by optical coherence tomography in vivo | journal=Eur Heart J | year= 2015 | volume= 38| issue= 6| pages= 447–455| pmid=26685129 | pmc=5837565 | doi=10.1093/eurheartj/ehv677}} [594] => * SAFI (species altered fluorescence imaging) an imaging technique in [[electrokinetic phenomena|electrokinetics]] and [[microfluidics]]. [595] => {{cite journal [596] => |pmid = 23463253 [597] => |url = https://microfluidics.stanford.edu/Publications/ParticleTracking_Diagnostics/Shkolnikov_A%20method%20for%20non-invasive%20full-field%20imaging%20and%20quantification%20of%20chemical%20species.pdf [598] => |year = 2013 [599] => |last1 = Shkolnikov [600] => |first1 = V [601] => |title = A method for non-invasive full-field imaging and quantification of chemical species [602] => |journal = Lab on a Chip [603] => |volume = 13 [604] => |issue = 8 [605] => |pages = 1632–43 [606] => |last2 = Santiago [607] => |first2 = J. G. [608] => |doi = 10.1039/c3lc41293h [609] => |url-status = live [610] => |archive-url = https://web.archive.org/web/20160305034642/https://microfluidics.stanford.edu/Publications/ParticleTracking_Diagnostics/Shkolnikov_A%20method%20for%20non-invasive%20full-field%20imaging%20and%20quantification%20of%20chemical%20species.pdf [611] => |archive-date = 5 March 2016 [612] => }} It uses non-electromigrating dyes whose fluorescence is easily quenched by migrating chemical species of interest. The dye(s) are usually seeded everywhere in the flow and differential quenching of their fluorescence by analytes is directly observed. [613] => * Fluorescence-based assays for screening [[Toxicity|toxic]] chemicals. The optical assays consist of a mixture of environment-sensitive fluorescent dyes and human skin cells that generate fluorescence spectra patterns. [614] => {{cite journal [615] => | pmid = 27653274 [616] => | pmc = 5031998 [617] => | year = 2016 [618] => | last1 = Moczko | first1 = E [619] => | title = Fluorescence-based assay as a new screening tool for toxic chemicals [620] => | journal = Scientific Reports [621] => | volume = 6 [622] => | page = 33922 [623] => | last2 = Mirkes | first2 = EM [624] => | last3 = Cáceres | first3 = C [625] => | last4 = Gorban | first4 = AN [626] => | last5 = Piletsky | first5 = S [627] => | doi = 10.1038/srep33922 [628] => | bibcode = 2016NatSR...633922M [629] => }} This approach can reduce the need for [[Animal testing|laboratory animals]] in biomedical research and pharmaceutical industry. [630] => *Bone-margin detection: [[Alizarin|Alizarin-stained]] specimens and certain fossils can be lit by fluorescent lights to view anatomical structures, including bone margins.{{Cite journal|last1=Smith|first1=W. Leo|last2=Buck|first2=Chesney A.|last3=Ornay|first3=Gregory S.|last4=Davis|first4=Matthew P.|last5=Martin|first5=Rene P.|last6=Gibson|first6=Sarah Z.|last7=Girard|first7=Matthew G.|date=2018-08-20|title=Improving Vertebrate Skeleton Images: Fluorescence and the Non-Permanent Mounting of Cleared-and-Stained Specimens|journal=Copeia|language=en-US|volume=106|issue=3|pages=427–435|doi=10.1643/cg-18-047|issn=0045-8511|doi-access=free}} [631] => [632] => === Forensics === [633] => [[Fingerprint]]s can be visualized with fluorescent compounds such as [[ninhydrin]] or DFO ([[1,8-Diazafluoren-9-one]]). Blood and other substances are sometimes detected by fluorescent reagents, like [[fluorescein]]. [[Fiber]]s, and other materials that may be encountered in [[Forensic science|forensics]] or with a relationship to various [[collectible]]s, are sometimes fluorescent. [634] => [635] => === Non-destructive testing === [636] => [[Fluorescent penetrant inspection]] is used to find cracks and other defects on the surface of a part. [[Dye tracing]], using fluorescent dyes, is used to find leaks in liquid and gas plumbing systems. [637] => [638] => === Signage === [639] => Fluorescent colors are frequently used in [[signage]], particularly road signs. Fluorescent colors are generally recognizable at longer ranges than their non-fluorescent counterparts, with fluorescent orange being particularly noticeable.Hawkins, H. Gene; Carlson, Paul John and Elmquist, Michael (2000) [http://d2dtl5nnlpfr0r.cloudfront.net/tti.tamu.edu/documents/2962-S.pdf "Evaluation of fluorescent orange signs"] {{webarchive|url=https://web.archive.org/web/20160304032241/http://d2dtl5nnlpfr0r.cloudfront.net/tti.tamu.edu/documents/2962-S.pdf |date=4 March 2016 }}, Texas Transportation Institute Report 2962-S. This property has led to its frequent use in safety signs and labels. [640] => [641] => === Optical brighteners === [642] => {{Main|Optical brightener}} [643] => Fluorescent compounds are often used to enhance the appearance of fabric and paper, causing a "whitening" effect. A white surface treated with an optical brightener can emit more visible light than that which shines on it, making it appear brighter. The blue light emitted by the brightener compensates for the diminishing blue of the treated material and changes the hue away from yellow or brown and toward white. Optical brighteners are used in laundry detergents, high brightness paper, cosmetics, [[high-visibility clothing]] and more. [644] => [645] => == See also == [646] => {{div col|colwidth=22em}} [647] => * Absorption-re-emission [[atomic line filter]]s use the phenomenon of fluorescence to filter light extremely effectively. [648] => * [[Black light]] [649] => * [[Blacklight paint]] [650] => * [[Fiber photometry]] [651] => * [[Fluorescence-activating and absorption-shifting tag]] [652] => * [[Fluorescence correlation spectroscopy]] [653] => * [[Fluorescence image-guided surgery]] [654] => * [[Fluorescence in plants]] [655] => * [[Fluorescence spectroscopy]] [656] => * [[Fluorescent lamp]] [657] => * [[Fluorescent Multilayer Disc]] [658] => * [[Fluorometer]] [659] => * [[High-visibility clothing]] [660] => * [[Integrated fluorometer]] [661] => * [[Laser-induced fluorescence]] [662] => * [[List of light sources]] [663] => * [[Microbial art]], using fluorescent bacteria [664] => * [[Mössbauer effect]], resonant fluorescence of gamma rays [665] => * [[Organic light-emitting diode]]s can be fluorescent [666] => * [[Phosphorescence]] [667] => * [[Phosphor thermometry]], the use of phosphorescence to measure temperature. [668] => * [[Spectroscopy]] [669] => * [[Two-photon absorption]] [670] => * [[Vibronic spectroscopy]] [671] => * [[X-ray fluorescence]] [672] => {{div col end}} [673] => [674] => == References == [675] => {{reflist|25em}} [676] => [677] => == Further reading == [678] => * {{cite book|year=1965|publisher=Raytech Industries|title=The Story of Fluorescence|url=https://www.fadedpage.com/showbook.php?pid=20181246}} [679] => [680] => == External links == [681] => {{commons category|Fluorescence}} [682] => * [https://archive.today/20121205013840/http://www.fluorophores.org/ Fluorophores.org], the database of fluorescent dyes [683] => * [http://micro.magnet.fsu.edu/primer/techniques/fluorescence/fluorescenceintro.html FSU.edu], Basic Concepts in Fluorescence [684] => * [http://www.lfd.uci.edu/workshop/2008/ "A nano-history of fluorescence" lecture by David Jameson] [685] => * [https://web.archive.org/web/20080527052150/http://www.mcb.arizona.edu/IPC/spectra_page.htm Excitation and emission spectra of various fluorescent dyes] [686] => * [http://www.fluomin.org/uk/list.php Database of fluorescent minerals with pictures, activators and spectra (fluomin.org)] [687] => * [https://www.youtube.com/watch?v=4V9TCdCbX6U "Biofluorescent Night Dive – Dahab/Red Sea (Egypt), Masbat Bay/Mashraba, "Roman Rock""]. YouTube. 9 October 2012. [688] => * Steffen O. Beyer. [https://web.archive.org/web/20140714155528/http://www.fluopedia.org/publications/ "FluoPedia.org: Publications"]. fluopedia.org. [689] => * Steffen O. Beyer. [http://www.fluomedia.org/science/ "FluoMedia.org: Science"]. fluomedia.org. [690] => [691] => {{Artificial light sources}} [692] => [693] => {{Authority control}} [694] => [695] => [[Category:Fluorescence| ]] [696] => [[Category:Dyes]] [697] => [[Category:Molecular biology]] [698] => [[Category:Radiochemistry]] [] => )

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Fluorescence

Fluorescence is a phenomenon in which certain atoms or molecules absorb and then re-emit light of a different, usually longer, wavelength. This emission occurs due to the absorption of energy from an external source, such as ultraviolet (UV) light, and is characterized by a rapid decay and emission of a fluorescent light.

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This emission occurs due to the absorption of energy from an external source, such as ultraviolet (UV) light, and is characterized by a rapid decay and emission of a fluorescent light. Fluorescence can be observed in various substances, such as minerals, dyes, and biological materials, and has important applications in fields such as biology, chemistry, and materials science. The Wikipedia page on fluorescence provides a detailed overview of the phenomenon, including its history, principles, mechanisms, and practical applications. It also discusses related topics, such as fluorophores, quantum yield, and fluorescence microscopy. The page covers the chemistry behind fluorescence, including the energy levels involved and the factors that influence fluorescence intensity. Additionally, it describes various techniques and instruments used to study fluorescence, such as fluorescence spectroscopy and fluorescence lifetime imaging microscopy.

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