Fluorescence is the emission of light by a substance that has absorbed
light or other electromagnetic radiation. It is a form of
luminescence. In most cases, the emitted light has a longer
wavelength, and therefore lower energy, than the absorbed radiation.
The most striking example of fluorescence occurs when the absorbed
radiation is in the ultraviolet region of the spectrum, and thus
invisible to the human eye, while the emitted light is in the visible
region, which gives the fluorescent substance a distinct color that
can only be seen when exposed to UV light. Fluorescent materials cease
to glow nearly immediately when the radiation source stops, unlike
phosphorescent materials, which continue to emit light for some time
Fluorescence has many practical applications, including mineralogy,
gemology, medicine, chemical sensors (fluorescence spectroscopy),
fluorescent labelling, dyes, biological detectors, cosmic-ray
detection, and, most commonly, fluorescent lamps.
occurs frequently in nature in some minerals and in various biological
states in many branches of the animal kingdom.
2 Physical principles
2.2 Quantum yield
2.4 Jablonski diagram
3.1 Kasha's rule
3.2 Mirror image rule
3.3 Stokes shift
Fluorescence in nature
4.1 Biofluorescence vs. bioluminescence vs. biophosphorescence
4.2 Mechanisms of biofluorescence
4.2.1 Epidermal chromatophores
4.3.1 Evolutionary origins
4.3.2 Adaptive functions
4.4 Aquatic biofluorescence
4.4.1 Photic zone
184.108.40.206 Mantis shrimp
4.4.2 Aphotic zone
4.5 Terrestrial biofluorescence
4.6 Abiotic fluorescence
4.6.1 Gemology, mineralogy and geology
4.6.2 Organic liquids
4.6.4 Common materials that fluoresce
5 Applications of fluorescence
5.2 Analytical chemistry
5.4 Biochemistry and medicine
5.4.2 Other techniques
5.6 Mechanical engineering
5.8 Optical brighteners
6 See also
9 External links
Lignum nephriticum cup made from the wood of the narra tree
(Pterocarpus indicus), and a flask containing its fluorescent solution
Matlaline, the fluorescent substance in the wood of the tree
An early observation of fluorescence was described in 1560 by
Bernardino de Sahagún
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. The chemical compound
responsible for this fluorescence is matlaline, which is the oxidation
product of one of the flavonoids found in this wood.
In 1819, Edward D. Clarke and in 1822 René Just Haüy described
fluorescence in fluorites,
Sir David Brewster
Sir David Brewster described the phenomenon
for chlorophyll in 1833 and
Sir John Herschel
Sir John Herschel did the same for
quinine in 1845.
In his 1852 paper on the "Refrangibility" (wavelength change) of
George Gabriel Stokes
George Gabriel Stokes described the ability of fluorspar and
uranium glass to change invisible light beyond the violet end of the
visible spectrum into blue light. He named this phenomenon
fluorescence : "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."
The name was derived from the mineral fluorite (calcium difluoride),
some examples of which contain 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 blue light emitted by an ethanol solution of
quinine exposed by it.
Fluorescence occurs when an orbital electron of a molecule, atom, or
nanostructure, relaxes to its ground state by emitting a photon from
an excited singlet state:
displaystyle S_ 0 +hnu _ ex to S_ 1
displaystyle S_ 1 to S_ 0 +hnu _ em +heat
is a generic term for photon energy with h =
Planck's constant and
= frequency of light. The specific frequencies of exciting and
emitted light are dependent on the particular system.
S0 is called the ground state of the fluorophore (fluorescent
molecule), and S1 is its first (electronically) excited singlet state.
A molecule in S1 can relax by various competing pathways. It can
undergo non-radiative relaxation in which the excitation energy is
dissipated as heat (vibrations) to the solvent. Excited organic
molecules can also relax via conversion to a triplet state, which may
subsequently relax via phosphorescence, or by a secondary
non-radiative relaxation step.
Relaxation from S1 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 ground state.
In most cases, the emitted light has a longer wavelength, and
therefore lower energy, than the absorbed radiation; this phenomenon
is known as the Stokes shift. However, when the absorbed
electromagnetic radiation is intense, it is possible for one electron
to absorb two photons; this two-photon absorption can lead to emission
of radiation having a shorter wavelength than the absorbed radiation.
The emitted radiation may also be of the same wavelength as the
absorbed radiation, termed "resonance fluorescence".
Molecules that are excited through light absorption or via a different
process (e.g. as the product of a reaction) can transfer energy to a
second 'sensitized' molecule, which is converted to its excited state
and can then fluoresce.
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.
Number of photons emitted
Number of photons absorbed
displaystyle Phi = frac text Number of photons emitted text
Number of photons absorbed
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
displaystyle Phi = frac k _ f sum _ i k _ i
displaystyle k _ f
is the rate constant of spontaneous emission of radiation and
displaystyle sum _ i k _ i
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:
dynamic collisional quenching, near-field dipole-dipole interaction
(or resonance energy transfer), internal conversion, and intersystem
crossing. Thus, if the rate of any pathway changes, both the excited
state lifetime and the fluorescence quantum yield will be affected.
Fluorescence quantum yields are measured by comparison to a standard.
The quinine salt quinine sulfate in a sulfuric acid solution is a
common fluorescence standard.
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.
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:
displaystyle left[S_ 1 right]=left[S_ 1 right]_ 0 e^ -
displaystyle left[S_ 1 right]
is the concentration of excited state molecules at time
displaystyle left[S_ 1 right]_ 0
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 the excited state. In such
case the total decay rate is the sum over all rates:
Gamma _ tot =
Gamma _ rad +
Gamma _ nrad
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 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.
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
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. 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 this 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 particular
Fluorescence anisotropy can be defined quantitatively as
displaystyle r= I_ parallel -I_ perp over I_ parallel +2I_
displaystyle I_ parallel
is the emitted intensity parallel to polarization of the excitation
displaystyle I_ perp
is the emitted intensity perpendicular to the polarization of the
Strongly fluorescent pigments often have an unusual appearance which
is often described colloquially as a "neon color." This phenomenon was
termed "Farbenglut" by
Hermann von Helmholtz
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.
There are several general rules that deal with fluorescence. Each of
the following rules has exceptions but they are useful guidelines for
understanding fluorescence (these rules do not necessarily apply to
Kasha's rule dictates that the quantum yield of luminescence is
independent of the wavelength of exciting radiation. This occurs
because excited molecules usually decay to the lowest vibrational
level of the excited state before fluorescence emission takes place.
The Kasha–Vavilov rule does not always apply and is violated
severely in many simple molecules. A somewhat more reliable statement,
although still with exceptions, would be that the fluorescence
spectrum shows very little dependence on the wavelength of exciting
Mirror image rule
For many fluorophores the absorption spectrum is a mirror image of the
emission spectrum. 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
Main article: Stokes shift
In general, emitted fluorescence light has a longer wavelength and
lower energy than the absorbed light. 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.
Fluorescence in nature
There are many natural compounds that exhibit fluorescence, and they
have a number of applications. Some deep-sea animals, such as the
greeneye, use fluorescence.
Biofluorescence vs. bioluminescence vs. biophosphorescence
Biofluorescence is the absorption of electromagnetic wavelengths from
the visible light spectrum by fluorescent proteins in a living
organism, and the emission of light at a lower energy level. This
causes the light that is emitted to be a different color than the
light that is absorbed. Stimulating light excites an electron, raising
energy to an unstable level. This instability is unfavorable, so the
energized electron is returned to a stable state almost as immediately
as it becomes unstable. This return to stability corresponds with the
release of excess energy in the form of fluorescence light. This
emission of light is only observable when the stimulant light is still
providing light to the organism/object and is typically yellow, pink,
orange, red, green, or purple. Biofluorescence is often confused with
the following forms of biotic light, bioluminescence and
Bioluminescence differs from biofluorescence in that it is the natural
production of light by chemical reactions within an organism, whereas
biofluorescence is the absorption and reemission of light from the
Biophosphorescence is similar to biofluorescence 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 biofluorescence, here the electron retains stability, emitting
light that continues to “glow-in-the-dark” even long after the
stimulating light source has been removed.
Mechanisms of biofluorescence
Pigment cells that exhibit fluorescence are called fluorescent
chromatophores, and function somatically similar to regular
chromatophores. 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. Fluorescent cells are
innervated the same as other chromatphores, 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.
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. Fish may also be
sensitive to cortisol induced stress responses to environmental
stimuli, such as interaction with a predator or engaging in a mating
It is suspected by some scientists that 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
Fluorescence has multiple origins in the tree of life. This diagram
displays the origins within actinopterygians (ray finned fish).
The incidence of fluorescence across the tree of life is widespread,
and has been studied most extensively in a phylogenetic sense in fish.
The phenomenon appears to have evolved multiple times in multiple 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 is one of the most common uses of fluorescence.
Currently, relatively little is known about the functional
significance of fluorescence and fluorescent proteins. However, it
is suspected that biofluorescence may serve important functions in
signaling and communication, mating, lures, camouflage, UV protection
and antioxidation, photoacclimation, dinoflagellate regulation, and in
coral health.
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, meaning cooler
colors dominate the visual field in the photic zone.
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.
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 biofluorescence, but enough light for other
organisms to detect it. 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 biofluorescent 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 biofluorescence 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 biofluorescence in the aphotic zone of the deep ocean
is an active area of research.
Fluorescent marine fish
Bony fishes living in shallow water, due to living in a colorful
environment, generally have good color vision. Thus, in shallow-water
fishes, red, orange, and green fluorescence most likely serves as a
means of communication with conspecifics, especially given the great
phenotypic variance of the phenomenon.
Many fish that exhibit biofluorescence, such as sharks, lizardfish,
scorpionfish, wrasses, and flatfishes, also possess yellow intraocular
filters. Yellow intraocular filters in the lenses and cornea of
certain fishes function as long-pass filters, thus enabling the
species that possess them to visualize and potentially exploit
fluorescence to enhance visual contrast and patterns that are unseen
to other fishes and predators that lack this visual
specialization. Fishes that possess the necessary yellow
intraocular filters for visualizing biofluorescence potentially
exploit a light signal from members of it or a similar functional
role. Biofluorescent patterning was especially prominent in
cryptically patterned fishes possessing complex camouflage, and that
many of these lineages also possess yellow long-pass intraocular
filters that could enable visualization of such patterns.
Another adaptive use of fluorescence is to generate 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. 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.
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.
Additionally, it is suggested that fluorescent 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
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.
Also, the proteins may fluctuate in number as more or less light
becomes available as a means of photoacclimation. Similarly, these
fluorescent proteins may possess antioxidant capacities to eliminate
oxygen radicals produced by photosynthesis. Finally, through
modulating photosynthesis, the fluorescent proteins may also serve as
a means of regulating the activity of the coral’s photosynthetic
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
Aequoria victoria, biofluorescent jellyfish known for GFP
Another, well-studied example of biofluorescence 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.
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.
Siphonophorae is an order of marine animals from the phylum Hydrozoa
that consist of a specialized medusoid and 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.
The predatory deep-sea dragonfish Malacosteus niger, the closely
related Aristostomias genus and the species Pachystomias microdon are
capable of harnessing the blue light emitted from their own
bioluminescence to generate red biofluorescence from suborbital
photophores. This red fluorescence is invisible to other animals,
which allows these dragonfish extra light at dark ocean depths without
attracting or signaling predators.
The Polka-dot tree frog, widely found in the Amazon was discovered to
be the first fluorescent amphibian in 2017. The frog is pale green
with dots in white, yellow or light red. The fluorescence of the frog
was discovered unintentionally in Buenos Aires, Argentina. The
fluorescence was traced to a new compound found in the lymph and skin
glads. The main fluorescent compound is Hyloin-L1 and it gives a
blue-green glow when exposed to violet or ultra violet light.
Scientists behind the discovery say that the fluorescence can be used
for communication. They also think that about 100 or 200 species of
frogs are likely to be fluorescent.
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.
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.
Spiders fluoresce under
UV light and possess a huge diversity of
fluorophores. Remarkably, 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.” A study by Andrews et al. (2007) reveals that
fluorescence has evolved multiple times across spider taxa, with novel
fluorophores evolving during spider diversification. In some spiders,
ultraviolet cues are important for predator-prey interactions,
intraspecific communication, and camouflaging with matching
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.
Scorpions also fluoresce.
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
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.
Chlorophyll fluoresces a weak red under ultraviolet light.
Gemology, mineralogy and geology
Fluorescence of Aragonite
Gemstones, minerals, may have a distinctive fluorescence or may
fluoresce differently under short-wave ultraviolet, long-wave
ultraviolet, visible light, or X-rays.
Many types of calcite and amber will fluoresce under shortwave UV,
longwave UV and visible light. Rubies, emeralds, and diamonds exhibit
red fluorescence under long-wave UV, blue and sometimes green light;
diamonds also emit light under
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, 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, 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 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.
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.
Organic 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
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 counters to detect such particles.
Stilbene is also one
of the gain mediums used in dye lasers.
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
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
Applications of fluorescence
Further information: Fluorescent lamp
Fluorescent paint and plastic lit by UV tubes. Paintings by Beo Beyond
The common fluorescent lamp relies on fluorescence. Inside the glass
tube is a partial vacuum and a small amount of 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 the ultraviolet 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 than 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.
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 efficiency with phosphor enhancement for better color
White light-emitting diodes (LEDs) became available in the mid-1990s
as LED lamps, 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
Glow sticks sometimes utilize fluorescent materials to absorb light
from the chemiluminescent reaction and emit light of a different
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
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 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.
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
transitions. To separate and analyze them, the fluorescent radiation
is passed through an emission monochromator, and observed selectively
by a detector.
Biochemistry and medicine
Fluorescence in the life sciences
Endothelial cells under the microscope with three separate channels
marking specific cellular components
Fluorescence in the life sciences
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). 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.
The quantification of a dye is done with a spectrofluorometer and
finds additional applications in:
When scanning the fluorescence intensity across a plane one has
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
DNA microarrays are a variant of this.
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.
Fluorescence Lifetime Imaging Microscopy) can be used to detect
certain bio-molecular interactions that manifest themselves by
influencing fluorescence lifetimes.
Cell and molecular biology: detection of colocalization using
fluorescence-labelled antibodies for selective detection of the
antigens of interest using specialized software, such as CoLocalizer
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
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 excited by a UV source, and the identity of the
base terminating the molecule is identified by the wavelength of the
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).
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
Fluorescence image-guided surgery) is a medical imaging
technique that uses fluorescence to detect properly labeled structures
Intravascular fluorescence is a catheter-based medical imaging
technique that uses fluorescence to detect high-risk features of
atherosclerosis and unhealed vascular stent devices. Plaque
autofluorescence has been used in a first-in-man study in coronary
arteries in combination with optical coherence tomography.
Molecular agents has been also used to detect specific features, such
as stent fibrin accumulation and enzymatic activity related to artery
SAFI (species altered fluorescence imaging) an imaging technique in
electrokinetics and microfluidics. 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
Fluorescence-based assays for screening toxic chemicals. The optical
assays consist of a mixture of environmental-sensitive fluorescent
dyes and human skin cells that generate fluorescence spectra
patterns. This approach can reduce the need for laboratory animals
in biomedical research and pharmaceutical industry.
Fingerprints 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.
Fibers, and other materials that may be encountered in forensics or
with a relationship to various collectibles, are sometimes
Fluorescent penetrant inspection
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.
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. This property has led to its frequent use
in safety signs and labels.
Main article: Optical brightener
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.
Absorption-re-emission atomic line filters use the phenomenon of
fluorescence to filter light extremely effectively.
Fluorescence correlation spectroscopy
Fluorescence image-guided surgery
Fluorescence in plants
Fluorescent multilayer card
Fluorescent Multilayer Disc
List of light sources
Microbial art, using fluorescent bacteria
Mössbauer effect, resonant fluorescence of gamma rays
Organic light-emitting diodes can be fluorescent
Phosphor thermometry, the use of phosphorescence to measure
^ a b Acuña, A. Ulises; Amat-Guerri, Francisco; Morcillo,
Purificación; Liras, Marta; Rodríguez, Benjamín (2009). "Structure
and Formation of the Fluorescent Compound of Lignum nephriticum"
(PDF). Organic Letters. 11 (14): 3020–3023. doi:10.1021/ol901022g.
PMID 19586062. Archived (PDF) from the original on 28 July
^ Safford, William Edwin (1916). "Lignum nephriticum". Annual report
of the Board of Regents of the Smithsonian Institution (PDF).
Washington: Government Printing Office. pp. 271–298.
^ Valeur, B.; Berberan-Santos, M. R. N. (2011). "A Brief History of
Phosphorescence before the Emergence of Quantum
Theory". Journal of Chemical Education. 88 (6): 731–738.
^ Muyskens, M.; Ed Vitz (2006). "The
Fluorescence of Lignum
nephriticum: A Flash Back to the Past and a Simple Demonstration of
Natural Substance Fluorescence". Journal of Chemical Education. 83
(5): 765. Bibcode:2006JChEd..83..765M. doi:10.1021/ed083p765.
^ Clarke, Edward Daniel (1819). "Account of a newly discovered variety
of green fluor spar, of very uncommon beauty, and with remarkable
properties of colour and phosphorescence". The Annals of Philosophy.
14: 34–36. Archived from the original on 17 January 2017. 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
^ Haüy merely repeats Clarke's observation regarding the colors of
the specimen of fluorite which he (Clarke) had examined: Haüy,
Traité de Minéralogie, 2nd ed. (Paris, France: Bachelier and Huzard,
1822), vol. 1, p. 512 Archived 17 January 2017 at the Wayback
Fluorite is called "chaux fluatée" by Haüy: "... violette
par réflection, et verdâtre par transparence au Derbyshire." ([the
color of fluorite is] violet by reflection, and greenish by
transmission in [specimens from] Derbyshire.)
^ Brewster, David (1834). "On the colours of natural bodies".
Transactions of the Royal Society of Edinburgh. 12 (2): 538–545.
doi:10.1017/s0080456800031203. Archived from the original on 17
January 2017. On page 542, Brewster mentions that when white
light passes through an alcoholic solution of chlorophyll, red light
is reflected from it.
^ Herschel, John (1845). "On a case of superficial colour presented by
a homogeneous liquid internally colourless". Philosophical
Transactions of the Royal Society of London. 135: 143–145.
doi:10.1098/rstl.1845.0004. Archived from the original on 24 December
^ Herschel, John (1845). "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"".
Philosophical Transactions of the Royal Society of London. 135:
147–153. doi:10.1098/rstl.1845.0005. Archived from the original on
17 January 2017.
^ Stokes, G. G. (1852). "On the Change of Refrangibility of Light".
Philosophical Transactions of the Royal Society of London. 142:
463–562. doi:10.1098/rstl.1852.0022. Archived from the original on
17 January 2017. From page 479, footnote: "I am almost inclined
to coin a word, and call the appearance fluorescence, from fluor-spar,
as the analogous term opalescence is derived from the name of a
^ Stokes (1852), pages 472–473. In a footnote on page 473, Stokes
acknowledges that in 1843, Edmond Becquerel had observed that quinine
acid sulfate strongly absorbs ultraviolet radiation (i.e., solar
radiation beyond Fraunhofer's H band in the solar spectrum). See:
Edmond Becquerel (1843) "Des effets produits sur les corps par les
rayons solaires" Archived 31 March 2013 at the Wayback Machine. (On
the effects produced on substances by solar rays), Comptes rendus,
17 : 882–884; on page 883, Becquerel cites quinine acid sulfate
("sulfate acide de quinine") as strongly absorbing ultraviolet light.
^ Lakowicz, p. 1
^ Holler, F. James; Skoog, Douglas A. and Crouch, Stanley R. (2006)
Principles Of Instrumental Analysis. Cengage Learning.
^ Lakowicz, p. 10
^ Valeur, Bernard, Berberan-Santos, Mario (2012). Molecular
Fluorescence: Principles and Applications. Wiley-VCH.
ISBN 978-3-527-32837-6. p. 64
^ "Animation for the Principle of
Fluorescence and UV-Visible
Absorbance" Archived 9 June 2013 at the Wayback Machine..
^ Lakowicz, pp. 12–13
^ Valeur, Bernard, Berberan-Santos, Mario (2012). Molecular
Fluorescence: Principles and Applications. Wiley-VCH.
ISBN 978-3-527-32837-6. p. 186
^ Schieber, Frank (October 2001). "Modeling the Appearance of
Fluorescent Colors". Proceedings of the Human Factors and Ergonomics
Society Annual Meeting. 45 (18): 1324–1327.
^ IUPAC. Kasha–Vavilov rule – Compendium of Chemical Terminology,
2nd ed. (the "Gold Book") Archived 21 March 2012 at the Wayback
Machine.. Compiled by McNaught, A.D. and Wilkinson, A. Blackwell
Scientific Publications, Oxford, 1997.
^ Lakowicz, pp. 6–8
^ Lakowicz, pp. 6–7
^ a b c "
Fluorescence in marine organisms". Gestalt Switch
Expeditions. Archived from the original on 21 February 2015.
^ a b c d Wucherer, M. F.; Michiels, N. K. (2012). "A Fluorescent
Chromatophore Changes the Level of
Fluorescence in a Reef Fish". PLoS
ONE. 7 (6): e37913. Bibcode:2012PLoSO...737913W.
doi:10.1371/journal.pone.0037913. PMC 3368913 .
^ Fujii, R (2000). "The regulation of motile activity in fish
chromatophores". Pigment cell research / sponsored by the European
Society for Pigment Cell Research and the International Pigment Cell
Society. 13 (5): 300–19. doi:10.1034/j.1600-0749.2000.130502.x.
^ Abbott, F. S. (1973). "Endocrine Regulation of
Fish". Integrative and Comparative Biology. 13 (3): 885–894.
^ a b Beyer, Steffen. "Biology of underwater fluorescence".
^ a b c d e Sparks, J. S.; Schelly, R. C.; Smith, W. L.; Davis, M. P.;
Tchernov, D.; Pieribone, V. A.; Gruber, D. F. (2014). Fontaneto,
Diego, ed. "The Covert World of Fish Biofluorescence: A
Phylogenetically Widespread and Phenotypically Variable Phenomenon".
PLoS ONE. 9 (1): e83259. Bibcode:2014PLoSO...983259S.
doi:10.1371/journal.pone.0083259. PMC 3885428 .
^ Matz, M. "Fluorescence: The Secret Color of the Deep". Office of
Ocean Exploration and Research, U.S. National Oceanic and Atmospheric
Administration. Archived from the original on 31 October 2014.
^ a b Heinermann, P (2014-03-10). "Yellow intraocular filters in
fishes". Experimental Biology. 43 (2): 127–147.
^ a b c d e Michiels, N. K.; Anthes, N.; Hart, N. S.; Herler, J. R.;
Meixner, A. J.; Schleifenbaum, F.; Schulte, G.; Siebeck, U. E.;
Sprenger, D.; Wucherer, M. F. (2008). "Red fluorescence in reef fish:
A novel signalling mechanism?". BMC Ecology. 8: 16.
doi:10.1186/1472-6785-8-16. PMC 2567963 .
^ Gerlach, T; Sprenger, D; Michiels, N. K. (2014). "Fairy wrasses
perceive and respond to their deep red fluorescent coloration".
Proceedings of the Royal Society B: Biological Sciences. 281 (1787):
20140787. doi:10.1098/rspb.2014.0787. PMC 4071555 .
^ Salih, A.; Larkum, A.; Cox, G.; Kühl, M.; Hoegh-Guldberg, O.
(2000). "Fluorescent pigments in corals are photoprotective". Nature.
408 (6814): 850–3. Bibcode:2000Natur.408..850S.
doi:10.1038/35048564. PMID 11130722. Archived from the original
on 22 December 2015.
^ Roth, M. S.; Latz, M. I.; Goericke, R.; Deheyn, D. D. (2010). "Green
fluorescent protein regulation in the coral Acropora yongei during
photoacclimation". Journal of Experimental Biology. 213 (21):
3644–3655. doi:10.1242/jeb.040881. PMID 20952612.
^ Bou-Abdallah, F.; Chasteen, N. D.; Lesser, M. P. (2006). "Quenching
of superoxide radicals by green fluorescent protein". Biochimica et
Biophysica Acta (BBA) - General Subjects. 1760 (11): 1690–1695.
doi:10.1016/j.bbagen.2006.08.014. PMC 1764454 .
^ Field, S. F.; Bulina, M. Y.; Kelmanson, I. V.; Bielawski, J. P.;
Matz, M. V. (2006). "Adaptive Evolution of Multicolored Fluorescent
Proteins in Reef-Building Corals". Journal of Molecular Evolution. 62
(3): 332–339. Bibcode:2006JMolE..62..332F.
doi:10.1007/s00239-005-0129-9. PMID 16474984.
^ Mäthger, L. M.; Denton, E. J. (2001). "Reflective properties of
iridophores and fluorescent 'eyespots' in the loliginid squid
Alloteuthis subulata and Loligo vulgaris". The Journal of Experimental
Biology. 204 (Pt 12): 2103–18. PMID 11441052. Archived from the
original on 4 March 2016.
^ Tsien, R. Y. (1998). "The Green Fluorescent Protein". Annual Review
of Biochemistry. 67: 509–544. doi:10.1146/annurev.biochem.67.1.509.
^ Mazel, C. H. (2004). "Fluorescent Enhancement of Signaling in a
Mantis Shrimp". Science. 303 (5654): 51. doi:10.1126/science.1089803.
^ Bou-Abdallah, F.; Chasteen, N. D.; Lesser, M. P. (2006). "Quenching
of superoxide radicals by green fluorescent protein". Biochimica et
Biophysica Acta (BBA) - General Subjects. 1760 (11): 1690–1695.
doi:10.1016/j.bbagen.2006.08.014. PMC 1764454 .
^ Douglas, R. H.; Partridge, J. C.; Dulai, K.; Hunt, D.; Mullineaux,
C. W.; Tauber, A. Y.; Hynninen, P. H. (1998). "Dragon fish see using
chlorophyll". Nature. 393 (6684): 423–424.
^ Wong, Sam (13 March 2017). "Luminous frog is the first known
naturally fluorescent amphibian". Archived from the original on 20
March 2017. Retrieved 22 March 2017.
^ King, Anthony (13 March 2017). "Fluorescent frog first down to new
molecule". Archived from the original on 22 March 2017. Retrieved 22
^ Vukusic, P; Hooper, I (2005). "Directionally controlled fluorescence
emission in butterflies". Science. 310 (5751): 1151.
doi:10.1126/science.1116612. PMID 16293753.
^ Arnold, K. E. (2002). "Fluorescent Signaling in Parrots". Science.
295 (5552): 92. doi:10.1126/science.295.5552.92.
PMID 11778040. [permanent dead link]
^ Andrews, K; Reed, S. M.; Masta, S. E. (2007). "Spiders fluoresce
variably across many taxa". Biology Letters. 3 (3): 265–7.
doi:10.1098/rsbl.2007.0016. PMC 2104643 .
^ Stachel, S. J.; Stockwell, S. A.; Van Vranken, D. L. (1999). "The
fluorescence of scorpions and cataractogenesis". Chemistry &
Biology. 6 (8): 531–539. doi:10.1016/S1074-5521(99)80085-4.
^ Iriel, A. A.; Lagorio, M. A. G. (2010). "Is the flower fluorescence
relevant in biocommunication?". Naturwissenschaften. 97 (10):
915–924. Bibcode:2010NW.....97..915I. doi:10.1007/s00114-010-0709-4.
^ McDonald, Maurice S. (2 June 2003). Photobiology of Higher Plants.
John Wiley & Sons. ISBN 9780470855232. Archived from the
original on 21 December 2017.
^ Gilmore, F. R.; Laher, R. R.; Espy, P. J. (1992). "Franck–Condon
Factors, r-Centroids, Electronic Transition Moments, and Einstein
Coefficients for Many Nitrogen and
Oxygen Band Systems". Journal of
Physical and Chemical Reference Data. 21 (5): 1005.
Bibcode:1992JPCRD..21.1005G. doi:10.1063/1.555910. Archived from the
original on 9 July 2017.
^ a b Harris, Tom. "How Fluorescent Lamps Work". HowStuffWorks.
Discovery Communications. Archived from the original on 6 July 2010.
Retrieved 27 June 2010.
^ Rye, H. S.; Dabora, J. M.; Quesada, M. A.; Mathies, R. A.; Glazer,
A. N. (1993). "Fluorometric Assay Using Dimeric Dyes for Double- and
DNA and RNA with Picogram Sensitivity". Analytical
Biochemistry. 208: 144–150. doi:10.1006/abio.1993.1020.
^ Harris, Daniel C. (2004). Exploring chemical analysis. Macmillan.
ISBN 978-0-7167-0571-0. Archived from the original on 31 July
^ Lakowicz, p. xxvi
^ Calfon MA, Vinegoni C, Ntziachristos V, Jaffer FA (2010).
"Intravascular near-infrared fluorescence molecular imaging of
atherosclerosis: toward coronary arterial visualization of
biologically high-risk plaques". J Biomed Opt. 15 (1): 011107.
PMC 3188610 . PMID 20210433.
^ Ughi GJ, Wang H, Gerbaud E, Gardecki JA, Fard AM, Hamidi E, et al.
(2016). "Clinical Characterization of Coronary Atherosclerosis With
Dual-Modality OCT and Near-Infrared
Autofluorescence Imaging". JACC
Cardiovasc Imaging. 9: 1304–1314. doi:10.1016/j.jcmg.2015.11.020.
PMC 5010789 . PMID 26971006.
^ Hara T, Ughi GJ, McCarthy JR, Erdem SS, Mauskapf A, Lyon SC, et al.
(2015). "Intravascular fibrin molecular imaging improves the detection
of unhealed stents assessed by optical coherence tomography in vivo".
Eur Heart J: ehv677. doi:10.1093/eurheartj/ehv677.
^ Shkolnikov, V; Santiago, J. G. (2013). "A method for non-invasive
full-field imaging and quantification of chemical species" (PDF). Lab
on a Chip. 13 (8): 1632–43. doi:10.1039/c3lc41293h.
PMID 23463253. Archived (PDF) from the original on 5 March
^ Moczko, E; Mirkes, EM; Cáceres, C; Gorban, AN; Piletsky, S (2016).
"Fluorescence-based assay as a new screening tool for toxic
chemicals". Scientific Reports. 6: 33922. Bibcode:2016NatSR...633922M.
doi:10.1038/srep33922. PMC 5031998 . PMID 27653274.
^ Hawkins, H. Gene; Carlson, Paul John and Elmquist, Michael (2000)
"Evaluation of fluorescent orange signs" Archived 4 March 2016 at the
Wayback Machine., Texas Transportation Institute Report 2962-S.
Lakowicz, Joseph R. (1999). Principles of
Kluwer Academic / Plenum Publishers.
Wikimedia Commons has media related to Fluorescence.
Fluorophores.org, the database of fluorescent dyes
FSU.edu, Basic Concepts in Fluorescence
"A nano-history of fluorescence" lecture by David Jameson
Excitation and emission spectra of various fluorescent dyes
Database of fluorescent minerals with pictures, activators and spectra
"Biofluorescent Night Dive – Dahab/Red Sea (Egypt), Masbat
Bay/Mashraba, "Roman Rock"". YouTube. 9 October 2012.
Steffen O. Beyer. "FluoPedia.org: Publications". fluopedia.org.
Steffen O. Beyer. "FluoMedia.org: Science". fluomedia.org.
Methods of generation
Parabolic aluminized reflector (PAR)
Fluorescent lamp (compact)
Hydrargyrum medium-arc iodide (HMI)
Hydrargyrum quartz iodide (HQI)
Stage lighting instrument
Intelligent street lighting