Fluorescence 1

Fluorescence

Fluorescent minerals emit visible light whenexposed to ultraviolet light

Fluorescence is the emission of light by a substance that has absorbedlight or other electromagnetic radiation. It is a form of luminescence.In most cases, the emitted light has a longer wavelength, and thereforelower energy, than the absorbed radiation. However, when theabsorbed electromagnetic radiation is intense, it is possible for oneelectron to absorb two photons; this two-photon absorption can lead toemission of radiation having a shorter wavelength than the absorbedradiation. The emitted radiation may also be of the same wavelength asthe absorbed radiation, termed "resonance fluorescence".[1]

The most striking examples of fluorescence occur when the absorbedradiation is in the ultraviolet region of the spectrum, and thus invisible to the human eye, and the emitted light is inthe visible region.

Fluorescence has many practical applications, including mineralogy, gemology, chemical sensors (fluorescencespectroscopy), fluorescent labelling, dyes, biological detectors, and, most commonly, fluorescent lamps.

History

Lignum nephriticum cup made fromthe wood of the narra tree

(Pterocarpus indicus), and a flaskcontaining its fluorescent solution

An early observation of fluorescence was described in 1560 by Bernardino deSahagún and in 1565 by Nicolás Monardes in the infusion known as lignumnephriticum (Latin for "kidney wood"). It was derived from the wood of two treespecies, Pterocarpus indicus and Eysenhardtia polystachya.[2][][3][4] Thechemical compound responsible for this fluorescence is matlaline, which is theoxidation product of one of the flavonoids found in this wood.[2]

In 1819, Edward D. Clarke[5] and in 1822 René Just Haüy[6] describedfluorescence in fluorites, Sir David Brewster described the phenomenon forchlorophyll in 1833[7] and Sir John Herschel did the same for quinine in 1845.[8]

In his 1852 paper on the "Refrangibility" (wavelength change) of light, GeorgeGabriel Stokes described the ability of fluorspar and uranium glass to changeinvisible light beyond the violet end of the visible spectrum into blue light. Henamed this phenomenon fluorescence : "I am almost inclined to coin a word, andcall the appearance fluorescence, from fluor-spar [i.e., fluorite], as the analogousterm opalescence is derived from the name of a mineral."[9] The name wasderived from the mineral fluorite (calcium difluoride), some examples of whichcontain traces of divalent europium, which serves as the fluorescent activator to

emit blue light. In a key experiment he used a prism to isolate ultraviolet radiation from sunlight and observed bluelight emitted by an ethanol solution of quinine exposed by it.[10]

Fluorescence 2

Matlaline, the fluorescent substance in the woodof the tree Eysenhardtia polystachya

Physical principles

Photochemistry

Fluorescence occurs when an orbital electron of a molecule, atom ornanostructure relaxes to its ground state by emitting a photon of lightafter being excited to a higher quantum state by some type ofenergy:[11]

Excitation: Fluorescence (emission): here is a generic term for photon energy with h = Planck's constantand = frequency of light. (The specific frequencies of exciting andemitted light are dependent on the particular system.)

State S0 is called the ground state of the fluorophore (fluorescent molecule) and S1 is its first (electronically) excitedstate.A molecule, S1, can relax by various competing pathways. It can undergo 'non-radiative relaxation' in which theexcitation energy is dissipated as heat (vibrations) to the solvent. Excited organic molecules can also relax viaconversion to a triplet state, which may subsequently relax via phosphorescence or by a secondary non-radiativerelaxation step.Relaxation of an S1 state can also occur through interaction with a second molecule through fluorescence quenching.Molecular oxygen (O2) is an extremely efficient quencher of fluorescence just because of its unusual triplet groundstate.Molecules that are excited through light absorption or via a different process (e.g. as the product of a reaction) cantransfer energy to a second 'sensitized' molecule, which is converted to its excited state and can then fluoresce. Thisprocess is used in lightsticks to produce different colors.

Quantum yieldThe fluorescence quantum yield gives the efficiency of the fluorescence process. It is defined as the ratio of thenumber of photons emitted to the number of photons absorbed.[12][13]

The maximum fluorescence quantum yield is 1.0 (100%); every photon absorbed results in a photon emitted.Compounds with quantum yields of 0.10 are still considered quite fluorescent. Another way to define the quantumyield of fluorescence, is by the rate of excited state decay:

where is the rate of spontaneous emission of radiation and

is the sum of all rates of excited state decay. Other rates of excited state decay are caused by mechanisms other thanphoton emission and are, therefore, often called "non-radiative rates", which can include: dynamic collisionalquenching, near-field dipole-dipole interaction (or resonance energy transfer), internal conversion, and intersystemcrossing. Thus, if the rate of any pathway changes, both the excited state lifetime and the fluorescence quantum yieldwill be affected.

Fluorescence 3

Fluorescence quantum yields are measured by comparison to a standard. The quinine salt quinine sulfate in a sulfuricacid solution is a common fluorescence standard.

Lifetime

Jablonski diagram. After an electron absorbs ahigh energy photon the system is excited

electronically and vibrationally. The systemrelaxes vibrationally, and eventually fluoresces at

a longer wavelength.

The fluorescence lifetime refers to the average time the molecule staysin its excited state before emitting a photon. Fluorescence typicallyfollows first-order kinetics:

where is the concentration of excited state molecules at time ,is the initial concentration and 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 theexcited state. In such case the total decay rate is the sum over all rates:

where is the total decay rate, the radiative decay rate andthe non-radiative decay rate. It is similar to a first-order

chemical reaction in which the first-order rate constant is the sum of allof the rates (a parallel kinetic model). If the rate of spontaneousemission, or any of the other rates are fast, the lifetime is short. Forcommonly used fluorescent compounds, typical excited state decaytimes for photon emissions with energies from the UV to near infraredare within the range of 0.5 to 20 nanoseconds. The fluorescencelifetime is an important parameter for practical applications offluorescence such as fluorescence resonance energy transfer andFluorescence-lifetime imaging microscopy.

Jablonski diagramThe Jablonski diagram describes most of the relaxation mechanisms for excited state molecules. The diagramalongside shows how fluorescence occurs due to the relaxation of certain excited electrons of a molecule.[11]

Fluorescence anisotropyFluorophores are more likely to be excited by photons if the transition moment of the fluorophore is parallel to theelectric vector of the photon.[14] The polarization of the emitted light will also depend on the transition moment. Thetransition moment is dependent on the physical orientation of the fluorophore molecule. For fluorophores in solutionthis means that 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 particularenvironment.Fluorescence anisotropy can be defined quantitatively as

where is the emitted intensity parallel to polarization of the excitation light and is the emitted intensityperpendicular to the polarization of the excitation light.[15]

Fluorescence 4

RulesThere are several general rules that deal with fluorescence. Each of the following rules has exceptions but they areuseful guidelines for understanding fluorescence. (These rules do not necessarily apply to Two-photon absorption.)

Kasha-Vavilov ruleThe Kasha–Vavilov rule dictates that the quantum yield of luminescence is independent of the wavelength ofexciting radiation.[16] This occurs because excited molecules usually decay to the lowest vibrational level of theexcited state before fluorescence emission takes place. The Kasha-Vavilov rule does not always apply and is violatedseverely in many simple molecules. A somewhat more reliable statement, although still with exceptions, would bethat the fluorescence spectrum shows very little dependence on the wavelength of exciting radiation.[citation needed]

Mirror image ruleFor many fluorophores the absorption spectrum is a mirror image of the emission spectrum.[17] This is known as themirror 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. Thismeans the nucleus does not move and the vibration levels of the excited state resemble the vibration levels of theground state.

Stokes shiftIn general, emitted fluorescent light has a longer wavelength and lower energy than the absorbed light.[18] Thisphenomenon, known as Stokes shift, is due to energy loss between the time a photon is absorbed and when it isemitted. The causes and magnitude of Stokes shift can be complex and are dependent on the fluorophore and itsenvironment. However, there are some common causes. It is frequently due to non-radiative decay to the lowestvibrational energy level of the excited state. Another factor is that the emission of fluorescence frequently leaves afluorophore in the highest vibrational level of the ground state.

Fluorescence in natureThere are many natural compounds that exhibit fluorescence, and they have a number of applications. Somedeep-sea animals, such as the greeneye, use fluorescence.

Gemology, mineralogy, and geologyGemstones, minerals, may have a distinctive fluorescence or may fluoresce differently under short-wave ultraviolet,long-wave ultraviolet, or X-rays.Many types of calcite and amber will fluoresce under shortwave UV. Rubies, emeralds, and the Hope Diamondexhibit red fluorescence under short-wave UV light; diamonds also emit light under X ray radiation.Fluorescence in minerals is caused by a wide range of 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, certain impurities such as iron or copper need to be absent, 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, 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 lanthanides such as terbium and dysprosium are the principal activators of the creamy

Fluorescence 5

yellow fluorescence exhibited by the yttrofluorite variety of the mineral fluorite, and contribute to the orangefluorescence of zircon. Powellite (calcium molybdate) and scheelite (calcium tungstate) fluoresce intrinsically inyellow and blue, respectively. When present together in solid solution, energy is transferred from the higher-energytungsten to the lower-energy molybdenum, such that fairly low levels of molybdenum are sufficient to cause ayellow emission for scheelite, instead of blue. Low-iron sphalerite (zinc sulfide), fluoresces and phosphoresces in arange of colors, influenced by the presence of various trace impurities.Crude oil (petroleum) fluoresces in a range of colors, from dull-brown for heavy oils and tars through tobright-yellowish and bluish-white for very light oils and condensates. This phenomenon is used in oil explorationdrilling to identify very small amounts of oil in drill cuttings and core samples.

Organic liquidsOrganic solutions such anthracene or stilbene, dissolved in benzene or toluene, fluoresce with ultraviolet or gammaray irradiation. The decay times of this fluorescence are of the order of nanoseconds, since the duration of the lightdepends on the lifetime of the excited states of the fluorescent material, in this case anthracene or stilbene.[citation

needed]

Common materials that fluoresce• Vitamin B2 fluoresces yellow.• Tonic water fluoresces blue due to the presence of quinine.• Highlighter ink is often fluorescent due to the presence of pyranine.• Banknotes, postage stamps and credit cards often have fluorescent security features.

Applications of fluorescence

Lighting

Fluorescent paint and plastic lit by UV tubes.Paintings by Beo Beyond

The common fluorescent lamp relies on fluorescence. Inside the glasstube is a partial vacuum and a small amount of mercury. An electricdischarge in the tube causes the mercury atoms to emit ultraviolet light.The tube is lined with a coating of a fluorescent material, called thephosphor, which absorbs the ultraviolet and re-emits visible light.Fluorescent lighting is more energy-efficient than incandescent lightingelements. However, the uneven spectrum of traditional fluorescentlamps may cause certain colors to appear different than whenilluminated by incandescent light or daylight. The mercury vaporemission spectrum is dominated by a short-wave UV line at 254 nm(which provides most of the energy to the phosphors), accompanied byvisible light emission at 436 nm (blue), 546 nm (green) and 579 nm (yellow-orange). These three lines can beobserved superimposed on the white continuum using a hand spectroscope, for light emitted by the usual whitefluorescent tubes. These same visible lines, accompanied by the emission lines of trivalent europium and trivalentterbium, and further accompanied by the emission continuum of divalent europium in the blue region, comprise themore discontinuous light emission of the modern trichromatic phosphor systems used in many compact fluorescentlamp and traditional lamps where better color rendition is a goal.[]

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 (HID) lamps couple their even-greater electrical

Fluorescence 6

efficiency with phosphor enhancement for better color rendition.[citation needed]

White light-emitting diodes (LEDs) became available in the mid-1990s as LED lamps, in which blue light emittedfrom the semiconductor strikes phosphors deposited on the tiny chip. The combination of the blue light thatcontinues through the phosphor and the green to red fluorescence from the phosphors produces a net emission ofwhite light.[citation needed]

Glow sticks sometimes utilize fluorescent materials to absorb light from the chemiluminescent reaction and emitlight of a different color.[]

Analytical chemistryMany analytical procedures involve the use of a fluorometer, usually with a single exciting wavelength and singledetection wavelength. Because of the sensitivity that the method affords, fluorescent molecule concentrations as lowas 1 part per trillion can be measured.[19]

Fluorescence in several wavelengths can be detected by an array detector, to detect compounds from HPLC flow.Also, TLC plates can be visualized if the compounds or a coloring reagent is fluorescent. Fluorescence is mosteffective when there is a larger ratio of atoms at lower energy levels in a Boltzmann distribution. There is, then, ahigher probability of excitement and release of photons by lower-energy atoms, making analysis more efficient.

SpectroscopyUsually the setup of a fluorescence assay involves a light source, which may emit many different wavelengths oflight. In general, a single wavelength is required for proper analysis, so, in order to selectively filter the light, it ispassed 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 variouselectron transitions. To separate and analyze them, the fluorescent radiation is passed through an emissionmonochromator, and observed selectively by a detector.[20]

Biochemistry and medicine

Endothelial cells under the microscope with threeseparate channels marking specific cellular

components

Fluorescence in the life sciences is used generally as a non-destructiveway of tracking or analysis of biological molecules by means of thefluorescent emission at a specific frequency where there is nobackground from the excitation light, as relatively few cellularcomponents are naturally fluorescent (called intrinsic orautofluorescence). In fact, a protein or other component can be"labelled" with an extrinsic fluorophore, a fluorescent dye that can be asmall molecule, protein, or quantum dot, finding a large use in manybiological applications.[21]

The quantification of a dye is done with a spectrofluorometer and findsadditional applications in:

Microscopy

• When scanning the fluorescent intensity across a plane one hasfluorescence microscopy of tissues, cells, or subcellular structures, which is accomplished by labeling an antibodywith a fluorophore and allowing the antibody to find its target antigen within the sample. Labelling multipleantibodies with different fluorophores allows visualization of multiple targets within a single image (multiplechannels). DNA microarrays are a variant of this.

Fluorescence 7

•• 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.

• FLIM (Fluorescence Lifetime Imaging Microscopy) can be used to detect certain bio-molecular interactions thatmanifest themselves by influencing fluorescence lifetimes.

• Cell and molecular biology: detection of colocalization using fluorescence-labelled antibodies for selectivedetection of the antigens of interest using specialized software, such as CoLocalizer Pro.

Other techniques

• FRET (Fluorescence resonance energy transfer or Förster resonance energy transfer) is used to study proteininteractions, detect specific nucleic acid sequences and used as biosensors, while fluorescence lifetime (FLIM)can give an additional layer of information.

• Biotechnology: biosensors using fluorescence are being studied as possible Fluorescent glucose biosensors.• 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 excitedby a UV source, and the identity of the base terminating the molecule is identified by the wavelength of theemitted light.

• FACS (fluorescence-activated cell sorting). One of several important cell sorting techniques used in theseparation of different cell lines (especially those isolated from animal tissues).

• DNA detection: the compound ethidium bromide, in aqueous solution, has very little fluorescence, as it isquenched by water. Ethidium bromide's fluorescence is greatly enhanced after it binds to DNA, so this compoundis very useful in visualising the location of DNA fragments in agarose gel electrophoresis. Intercalated ethidium isin a hydrophobic environment when it is between the base pairs of the DNA, protected from quenching by waterwhich is excluded from the local environment of the intercalated ethidium. Ethidium bromide may becarcinogenic – an arguably safer alternative is the dye SYBR Green.

• FIGS (Fluorescence image-guided surgery) is a medical imaging technique that uses fluorescence to detectproperly labeled structures during surgery.

• SAFI (species altered fluorescence imaging) an imaging technique in electrokinetics and microfluidics [22]. It usesnon-electromigrating dyes whose fluorescence is easily quenched by migrating chemical species of interest. Thedye(s) are usually seeded everywhere in the flow and differential quenching of their fluorescence by analytes isdirectly observed.

ForensicsFingerprints can be visualized with fluorescent compounds such as ninhydrin. Blood and other substances aresometimes detected by fluorescent reagents, like fluorescein. Fibers, and other materials that may be encountered inforensics or with a relationship to various collectibles, are sometimes fluorescent.

References[1] Principles Of Instrumental Analysis F.James Holler, Douglas A. Skoog & Stanley R. Crouch 2006[2] Available on-line at: Chinese Academy of Science (http:/ / 202. 127. 145. 151/ siocl/ siocl_0001/ HHJdatabank/ 090707ol-6. pdf).[5] Edward Daniel Clarke (1819) "Account of a newly discovered variety of green fluor spar, of very uncommon beauty, and with remarkable

properties of colour and phosphorescence," (http:/ / books. google. com/ books?id=KWc7AQAAIAAJ& pg=PA34#v=onepage& q& f=false)The Annals of Philosophy, 14 : 34 - 36; from page 35: "The finer crystals are perfectly transparent. Their colour by transmitted light is anintense emerald green; but by reflected light, the colour is a deep sapphire blue; … ".

[6] Haüy merely repeats Clarke's observation regarding the colors of the specimen of fluorite which he (Clarke) had examined: Haüy, Traité deMinéralogie, 2nd ed. (Paris, France: Bachelier and Huzard, 1822), vol. 1, page 512. Fluorite is called "chaux fluatée" by Haüy. From page 512(http:/ / books. google. com/ books?id=MvcTAAAAQAAJ& pg=PA512#v=onepage& q& f=false): "... violette par réflection, et verdâtre partransparence au Derbyshire." ([the color of fluorite is] violet by reflection, and greenish by transmission in [specimens from] Derbyshire.)

[7] David Brewster (1834) "On the colours of natural bodies," (http:/ / books. google. com/ books?id=I_UQAAAAIAAJ&

pg=PA538#v=onepage& q& f=false) Transactions of the Royal Society of Edinburgh 12 : 538-545; on page 542, Brewster mentions that when

Fluorescence 8

white light passes through an alcoholic solution of chlorophyll, red light is reflected from it.[8][8] See:

• Herschel, John (1845a) "On a case of superficial colour presented by a homogeneous liquid internally colourless," (http:/ / books. google.com/ books?id=GmwOAAAAIAAJ& pg=PA143#v=onepage& q& f=false) Philosophical Transactions of the Royal Society of London,135 : 143-145; see page 145.

• Herschel, John (1845b) "On the epipŏlic dispersion of light, being a supplement to a paper entitled, "On a case of superficial colourpresented by a homogeneous liquid internally colourless" ," (http:/ / books. google. com/ books?id=GmwOAAAAIAAJ&pg=PA147#v=onepage& q& f=false) Philosophical Transactions of the Royal Society of London, 135 : 147-153.

[9] From page 479, footnote: "I am almost inclined to coin a word, and call the appearance fluorescence, from fluor-spar, as the analogous termopalescence is derived from the name of a mineral."

[10] Stokes (1852), pages 472-473. In a footnote on page 473, Stokes acknowledges that in 1843, Edmond Becquerel had observed that quinineacid sulfate strongly absorbs ultraviolet radiation (i.e., solar radiation beyond Fraunhofer's H band in the solar spectrum). See: EdmondBecquerel (1843) "Des effets produits sur les corps par les rayons solaires" (http:/ / gallica. bnf. fr/ ark:/ 12148/ bpt6k2976b/ f894. image) (Onthe effects produced on substances by solar rays), Comptes rendus, 17 : 882-884; on page 883, Becquerel cites quinine acid sulfate ("sulfateacide de quinine") as strongly absorbing ultraviolet light.

[11] Animation for the principle of fluorescence and UV-visible absorbance (http:/ / pharmaxchange. info/ press/ 2013/ 03/animation-for-the-principle-of-fluorescence-and-uv-visible-absorbance/ )

[12][12] Lakowicz, Joseph R. Principles of Fluorescence Spectroscopy(second edition). Kluwer Academic / Plenum Publishers, 1999 p. 10[13] Valeur, Bernard, Berberan-Santos, Mario 2012. Molecular Fluorescence: Principles and Applications 2nd ed., Wiley-VCH, p. 64[14][14] Lakowicz, J. R. (1999). Principles of Fluorescence Spectroscopy. Kluwer Academic / Plenum Publishers pp 12-13[15] Valeur, Bernard, Berberan-Santos, Mario 2012. Molecular Fluorescence: Principles and Applications 2nd ed., Wiley-VCH, p.186[16] IUPAC. Kasha–Vavilov rule – Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (http:/ / goldbook. iupac. org/ K03371.

html). Compiled by McNaught, A.D. and Wilkinson, A. Blackwell Scientific Publications, Oxford, 1997.[17] Lakowicz, J. R. (1999). Principles of Fluorescence Spectroscopy. Kluwer Academic / Plenum Publishers pp 6–8[18] Lakowicz, J. R. (1999). Principles of Fluorescence Spectroscopy. Kluwer Academic / Plenum Publishers pp 6–7[19] "Fluorometric Assay Using Dimeric Dyes for Double- and Single-Stranded DNA and RNA with Picogram Sensitivity"; H.S. Rye, J.M.

Dabora, M.A. Quesada, R.A. Mathies, A.N. Glazer, Analytical Biochemistry, Volume 208, Issue 1, January 1993, Pages 144–150, http:/ / dx.doi. org/ 10. 1006/ abio. 1993. 1020

[22] https:/ / microfluidics. stanford. edu/ Publications/ ParticleTracking_Diagnostics/Shkolnikov_A%20method%20for%20non-invasive%20full-field%20imaging%20and%20quantification%20of%20chemical%20species. pdf

External links• Fluorophores.org (http:/ / www. fluorophores. org), the database of fluorescent dyes• FSU.edu (http:/ / micro. magnet. fsu. edu/ primer/ techniques/ fluorescence/ fluorescenceintro. html), Basic

Concepts in Fluorescence• "A nano-history of fluorescence" lecture by David Jameson (http:/ / www. lfd. uci. edu/ workshop/ 2008/ )• Excitation and emission spectra of various fluorescent dyes (http:/ / www. mcb. arizona. edu/ IPC/ spectra_page.

htm)• Database of fluorescent minerals with pictures, activators and spectra (fluomin.org) (http:/ / www. fluomin. org/

uk/ list. php)

Article Sources and Contributors 9

Article Sources and ContributorsFluorescence  Source: http://en.wikipedia.org/w/index.php?oldid=563478324  Contributors: 12 Noon, 1exec1, 2parkway, 777sms, 7yPDx4, 90 Auto, AGToth, AJim, Ablocknavitar, Aboalbiss,Abstraktn, Adi4094, Afluegel, Afvandriel, Aleena.lima, AlistairMcMillan, Allstarecho, Amigadave, Andres, Anlace, Arcadian, Arganoid, Arnaulds, Artgen, Ashleytaylor, Barry.b.benson,Bazzargh, Beetstra, Belovedfreak, BenFrantzDale, Beniaminobarbieri, Bensaccount, Billhpike, Biophysik, Blaxthos, Boardhead, Bombyx, Bormalagurski, Bovineboy2008, Brewhaha@edmc.net,Brian Kendig, CZ Micha, Caltas, Can't sleep, clown will eat me, Charles Clark, Cheakamus, Chetvorno, Chezi-Schlaff, Chinasaur, Chipotle, Chiu frederick, Chris 73, Chris the speller,ChrisGualtieri, Chrism, Chthonic, Cnickelfr, Conversion script, CronDaemon, Cwkmail, Cypoet, D.H, DV8 2XL, Daffman1408, David R. Ingham, Dcirovic, Deglr6328, Delmlsfan, Delta G,Denimadept, Deutschgirl, Dextery, DocWatson42, Donarreiskoffer, DoriSmith, Douglas E. Mitchell, Doulos Christos, Dpotter, Drmies, Drphilharmonic, E104421, Ed g2s, Eigenlambda, El C,Eluchil404, Emeraldfire33, Erianna, Farshid7, Fcsuper, Finell, Fredbauder, Fredrik, Funandtrvl, Gilliam, Gmoney484, Gogowitsch, Gordonjcp, Graeme Bartlett, Graham87, Guiltlessgecko,Gunnar Larsson, Götz, H Padleckas, Hankwang, Hauberg, Heds, Heron, Hgrobe, Howcheng, Huw Powell, Ian Glenn, Icairns, Ida Shaw, ImperatorExercitus, Imroy, Invertzoo, IronGargoyle,JRice, Jacobkhed, Jaeger5432, Jannik05, Jbunzli, Jeff Silvers, Jeniyoung, Jesse V., Jimw338, Joe Rodgers, JoeIdoni, John, Johnnydc, Jolyonralph, JonHarder, Jrockley, Julesd, Kakapo3,Katalaveno, Kkmurray, Kku, Kri, Kylemcinnes, L Kensington, La goutte de pluie, Lalo1121, Larryisgood, Looie, Lotje, MER-C, Maartend8, Malcolm Farmer, Marie Poise, Materialscientist,Maupertius, Mehothra, Meisam.fa, MelindaSA, Mervyn, Mexaguil, Mgambrell, Michael Hardy, Michael Snow, Michi zh, Mild Bill Hiccup, Mintz l, Mion, Mllyjn, Monkey Bounce, Moops1989,MrOllie, MrZap, Mythealias, Nathan.C.Heston, Negativecharge, Newone, Nigelj, Nono64, Notinasnaid, Nuno Tavares, Obsidian Soul, Ocaasi, Olivier2310, Omegatron, Omes, Onco p53,Oxymoron83, Panoramix303, ParisianBlade, Pedrose, Petergans, Philip Trueman, Pj.de.bruin, Prodego, Qwyrxian, Redrose64, RenOfHeavens, Ringler, Rjwilmsi, Rna2600, Rod57, Rogper,Ronningt, Rotational, Rtstgaf, Rumpuscat, Ryulong, SPKirsch, Sandsturs, Sentausa, Shanata, Shloimeborukh, Silentviking, SimonP, Slicky, Smalljim, Snags, Snappyh, Soewinhan,SpareHeadOne, Spellmaster, Splarka, Squidonius, Srleffler, St3vo, Steve Quinn, Stiner905, Stormie, Storslem, Strangefrogs, Sun Creator, Suto, Tabletop, Techsmith, Templatehater, Teratornis,The Anome, The Famous Movie Director, The Singularity, The Thing That Should Not Be, The wub, Theron110, Thewire, Tim1357, Tom Pippens, TomPreuss, Travis Evans, Trelvis, Tylerni7,Untionic, V8rik, Valfontis, Vanished User 1004, Vanished user vjhsduheuiui4t5hjri, Venny85, Verne Equinox, Vicarious, WahreJakob, Welsh, Widr, Wikipelli, Wiz-Pro3, Wrfrancis, WritKeeper, WriterHound, Wsloand, Wtshymanski, Xan81, Xiornik, Yath, Yintan, Z10x, ZayZayEM, Zbxgscqf, Ζεύς, 389 anonymous edits

Image Sources, Licenses and ContributorsImage:Fluorescent minerals hg.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Fluorescent_minerals_hg.jpg  License: Creative Commons Attribution-Sharealike 2.5  Contributors:Hannes Grobe (Hgrobe 06:16, 26 April 2006 (UTC))File:Lignum nephriticum - cup of Philippine lignum nephriticum, Pterocarpus indicus, and flask containing its fluorescent solution Hi.jpg  Source:http://en.wikipedia.org/w/index.php?title=File:Lignum_nephriticum_-_cup_of_Philippine_lignum_nephriticum,_Pterocarpus_indicus,_and_flask_containing_its_fluorescent_solution_Hi.jpg License: Public Domain  Contributors: Obsidian SoulFile:Matlaline -- fluorescent substance from Mexican tree, Eysenhardtia polystachya.JPG  Source:http://en.wikipedia.org/w/index.php?title=File:Matlaline_--_fluorescent_substance_from_Mexican_tree,_Eysenhardtia_polystachya.JPG  License: Creative Commons Attribution-Sharealike 3.0 Contributors: User:CwkmailFile:Jablonski Diagram of Fluorescence Only.png  Source: http://en.wikipedia.org/w/index.php?title=File:Jablonski_Diagram_of_Fluorescence_Only.png  License: Creative Commons Zero Contributors: User:JacobkhedImage:Www Beo cc.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Www_Beo_cc.jpg  License: Creative Commons Attribution-Sharealike 3.0  Contributors: Beo BeyondImage:FluorescentCells.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:FluorescentCells.jpg  License: Public Domain  Contributors: Amada44, DO11.10, Daniel Mietchen, Emijrp,Hannes Röst, Liaocyed, NEON ja, Origamiemensch, Sentausa, Splette, Timur lenk, Tolanor, Túrelio, 8 anonymous edits

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