phosphor

(noun)

A substance that exhibits the phenomenon of luminescence; often transition metal compounds or rare earth compounds of various types. The most common uses of phosphors are in CRT displays and fluorescent lights.

Related Terms

  • raster
  • electron gun

Examples of phosphor in the following topics:

  • The Phosphorus Cycle

    • Plants assimilate phosphorous from the environment and then convert it from inorganic phosphorous to organic phosphorous.
    • The organic phosphorous is released and converted back into inorganic phosphorous through decomposition.
    • Much of the phosphorous is then converted to organic phosphorous, and primary productivity then declines.
    • The phosphorous cycle is affected by human activities.
    • Although phosphorous is normally a limiting nutrient, most agricultural fertilizers contain phosphorous.
  • Cathode Ray Tube, TV and Computer Monitors, and the Oscilloscope

    • The images are generated when electrons strike fluorescent phosphors on the screen, which then emit light (the color varies depending on the phosphor used, ).
    • By varying the type of phosphor used, one may vary the wavelength of light emitted by the phosphor when excited.
    • Early computer terminal monitors used only green phosphors.
    • For visual observation of brief transient events, a long persistence phosphor may be desirable.
    • Monochrome monitor - this CRT uses only one type of phosphor.
  • Phosphorus Compounds

    • For this purpose, phosphate-containing minerals are converted to phosphoric acid.
    • Although many oxoacids of phosphorus are formed, only nine are important, and three are crucial: hypophosphorous acid, phosphorous acid, and phosphoric acid.
    • Phosphorous acid, H3PO3, contains two acidic OH bonds and one PH bond.
    • Since it is triprotic, phosphoric acid converts stepwise to three conjugate bases:
    • Phosphoric acid contains one P=O double bond and three P-O single bonds terminating in acidic OH groups.
  • Sources and Sinks of Essential Elements

    • The nitrogen cycle, the phosphorous cycle, the sulfur cycle, and the carbon cycle all involve assimilation of these nutrients into living things.
    • Likewise, phosphorous and nitrogen are extracted from geological reservoirs and used in phosphorous, and excesses of these elements have caused the overgrowth of plant matter and the disruption of many ecosystems.
  • Calculating Equilibrium Concentrations of Polyprotic Acids

    • Common polyprotic acids include sulfuric acid (H2SO4), and phosphoric acid (H3PO4).
    • Thus, in an aqueous solution of phosphoric acid, there will theoretically be seven ionic and molecular species present: H3PO4, H2PO4-, HPO42-, PO43-, H2O, H+, and OH-.
    • Take for instance the second dissociation step of phosphoric acid, which has a pKa2 of 7.21:
    • The chemical structure of phosphoric acid indicates it has three acidic protons.
  • Alloys

    • Examples of alloys include materials such as brass, pewter, phosphor bronze, amalgam, and steel.
    • Examples of alloys include materials such as brass, pewter, phosphor bronze, amalgam, and steel.
  • Nucleophilicity of Phosphorus Compounds

    • Phosphorous analogs of amines are called phosphines.
  • Diprotic and Polyprotic Acids

    • Two common examples are carbonic acid (H2CO3, which has two acidic protons and is therefore a diprotic acid) and phosphoric acid (H3PO4, which has three acidic protons and is therefore a triprotic acid).
    • Take, for example the three dissociation steps of the common triprotic acid phosphoric acid:
  • Mercury

    • It is also used in lighting—electricity passed through mercury vapor in a phosphor tube produces short-wave ultraviolet light, causing the phosphor to fluoresce and produce visible light.
  • Elimination Reactions of Alcohols

    • The conjugate bases of sulfuric and phosphoric acids are not good nucleophiles and do not give substitution under the usual conditions of their use.
    • The E2 elimination of 3Âș-alcohols under relatively non-acidic conditions may be accomplished by treatment with phosphorous oxychloride (POCl3) in pyridine.
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