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The Collaborative International Dictionary

Fluorescence \Flu`o*res"cence\, n. [From Fluor.] (Chemistry, Optics) A luminescence emitted by certain substances due to the absorption of radiation at one wavelength, and the almost instantaneous re-emission of radiation at another, usually longer wavelength. The re-radiation stops almost as soon as the incident radiation is halted, thus distinguishing this phenomenon from phosphorescence, in which re-radiation of light may continue for some time after the incident radiation is halted.

Note: The color of the radiated light typically differs from the apparent color of the material, as when green crystals of fluor spar afford blue reflections. It is due not to the difference in the color of a distinct surface layer, but to the power which the substance has of modifying the light incident upon it, by first absorbing the light to achieve an excited state, and then radiating light to resume the ground energy level. The light emitted by fluorescent substances is in general of longer wavelength than the incident light. The radiation can also be induced by ionizing radiation which is not electromagnetic, such as alpha or beta rays, and cathode rays. This property is possessed by fluorspar, uranium glass, sulphide of calcium, and many other substances. It finds use in analytical instruments to detect or measure radiation, and in some commercial applications.

Douglas Harper's Etymology Dictionary

1852, "property of glowing in ultraviolet light," coined by English mathematician and physicist Sir George G. Stokes (1819-1903) from fluorspar (see fluorine), because in it he first noticed the phenomenon, + -escence, on analogy of phosphorescence.


n. 1 (context physics English) The emission of light (or other electromagnetic radiation) by a material when stimulated by the absorption of radiation or of a subatomic particle 2 The light so emitted


n. light emitted during absorption of radiation of some other (invisible) wavelength


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. However, unlike phosphorescence, where the substance would continue to glow and emit light for some time after the radiation source has been turned off, fluorescent materials would cease to glow immediately upon removal of the excitation source. Hence, it is not a persistent phenomenon.

Fluorescence has many practical applications, including mineralogy, gemology, chemical sensors ( fluorescence spectroscopy), fluorescent labelling, dyes, biological detectors, cosmic-ray detection, and, most commonly, fluorescent lamps. Fluorescence also occurs frequently in nature in some minerals and in various biological states in many branches of the animal kingdom.

Fluorescence (album)

Fluorescence is the fourth studio album by New York-based shoegaze band Asobi Seksu. It was released on February 14, 2011. It was released on CD and vinyl by Polyvinyl Record Co.. A limited-edition pink marble vinyl pressing was available for the first 1,500 purchases.

Usage examples of "fluorescence".

A blast of overhead fluorescence interrupted the usual jailhouse gloom and leaked into the hall through a narrow plateglass panel in the door meant to allow observation by patrolling guards.

All these old sober Boston blue-collar men's irrevocable tattoos fading almost observably under the low-budget fluorescence of church basements and hospital auditoria Ewell watched and charted and cross-referenced them, moved.

The light stutters and hums and bathes the counter with cold lithium-free fluorescence.

Microscopy, infrared spectrophotometry, pyrolysis-gas chromatography, mass spectrometry, x-ray fluorescence, and neutron activation analysis were not required to figure out that much.

She made the camera move in and out and around, illuminate murky recesses, magnify, induce fluorescence.

But she could see slightly glossier versions of her own fluorescence, stainless steel, ceramic island, rubber tile, pastel enamels, warm wood paneling in the Hollywood product on both Big Screen and home tube, so there she was on the set, and she had to say the lines, but after you said the lines enough times All of a sudden you'd get interrupted by something a little more direct than a commercial message from your sponsor.

Here was the X-ray fluorescence spectrometer, for instance, an anonymous grey box which looked like an industrial-strength photocopier, into which ground-up fragments of his rocks were fed in tiny platinum egg cups.

Stood in the cold fluorescence and opened it up to D for the Dallas-Fort Worth departures and ran his finger down the list of destinations as far as H for Honolulu.

The rhizome also contains Gelsemic acid a crystalline substance which exhibits an intense bluish-green fluorescence in alkaline solution.

Only the imparities glow under its fluorescence, thus giving you an idea of the quality of the coke.

Some bloody, broken, moaning teenagers were being offloaded from a white ambulance with blue dome lights, and wheeled through the double doors into a corridor glare of fluorescence so strong and white it made the blood look black.

The colored fluorescence gleaming through the slits of polarized molecular film turned his cool, smooth face into something unearthly.

We came through a series of ramps and stairs into the huge, bleak room at the pit of the ship lighted by only the thin glow of fluorescence, with the dark hum of the transistors the only sound in all of these spaces and it was there at last where I halted him, motioning him with a gesture to move back against one of the walls while I stood across from him.

With it we might be able to detect fluorescence from considerable distances, and record its density on photographic film.

There was bright fluorescence in the office and in the narrow stock room beyond the office.