Fluorescence

Fluorescence
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. [1913 Webster +PJC]


The Collaborative International Dictionary of English. 2000.

Игры ⚽ Поможем решить контрольную работу

Look at other dictionaries:

  • fluorescence — [ flyɔresɑ̃s ] n. f. • 1856; mot angl. (1852), de fluor, d apr. phosphorescence ♦ Phys. Luminescence d une substance (solide, liquide ou gaz) due à une transition spontanée des molécules, d un état excité vers l état fondamental. Fluorescence… …   Encyclopédie Universelle

  • fluorescence — 1852, glowing in ultraviolet light, coined by English mathematician and physicist Sir George G. Stokes (1819 1903) from fluorspar (see FLUORINE (Cf. fluorine)), because in it he first noticed the phenomenon, + ESCENCE (Cf. escence), on analogy of …   Etymology dictionary

  • fluorescence —  Fluorescence  Флуоресценция   Кратковременная люминесценция. Излучательный переход между двумя состояниями одинаковой мультиплетности (синглетными или триплетными уровнями). Флуоресценция наблюдается в жидкой, твердой и газовой фазах. При… …   Толковый англо-русский словарь по нанотехнологии. - М.

  • fluorescence — ► NOUN 1) light emitted by a substance when it is exposed to radiation such as ultraviolet light or X rays. 2) the property of emitting light in this way. ORIGIN from FLUORSPAR(Cf. ↑F) (which fluoresces), on the pattern of opalescence …   English terms dictionary

  • fluorescence — [flo͞o΄ə res′əns] n. [< FLUOR(SPAR) + ESCENCE] 1. the property of a substance, such as fluorite, of producing light while it is being acted upon by ultraviolet rays, X rays, or other forms of radiant energy 2. the production of such light 3.… …   English World dictionary

  • Fluorescence — Fluorescent minerals emit visible light when exposed to ultraviolet light Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation of a different wavelength.[1] It is a form of luminescence.… …   Wikipedia

  • Fluorescence X — Spectrométrie de fluorescence X Pour les articles homonymes, voir SFX, FX et XRF. Un spectromètre de fluorescence X Philips PW1606 avec manutention automatiq …   Wikipédia en Français

  • Fluorescence — La fluorescence est une émission lumineuse provoquée par l excitation d une molécule (généralement par absorption d un photon) immédiatement suivie d une émission spontanée. Ce processus est différent de la phosphorescence. La fluorescence peut… …   Wikipédia en Français

  • fluorescence — /floo res euhns, flaw , floh /, n. Physics, Chem. 1. the emission of radiation, esp. of visible light, by a substance during exposure to external radiation, as light or x rays. Cf. phosphorescence (def. 1). 2. the property possessed by a… …   Universalium

  • fluorescence — (flu o rè ssan s ) s. f. Terme de physique. Éclairement particulier que présentent certaines substances lorsqu elles sont exposées à l action des parties les plus réfrangibles de la radiation lumineuse, c est à dire à l action des rayons… …   Dictionnaire de la Langue Française d'Émile Littré

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”