photosensitization


photosensitization
pho·to·sen·si·ti·za·tion (fō'tō-sĕn'sĭ-tĭ-zāʹshən) n.
The act or process of inducing photosensitivity.

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      the process of initiating a reaction through the use of a substance capable of absorbing light and transferring the energy to the desired reactants. The technique is commonly employed in photochemical work, particularly for reactions requiring light sources of certain wavelengths that are not readily available. A commonly used sensitizer is mercury, which absorbs radiation at 1849 and 2537 angstroms; these are the wavelengths of light produced in high-intensity mercury lamps. Also used as sensitizers are cadmium; some of the noble gases, particularly xenon; zinc; benzophenone; and a large number of organic dyes.

      In a typical photosensitized reaction, as in the photodecomposition of ethylene to acetylene and hydrogen, a mixture of mercury vapour and ethylene is irradiated with a mercury lamp. The mercury atoms absorb the light energy, there being a suitable electronic transition in the atom that corresponds to the energy of the incident light. In colliding with ethylene molecules, the mercury atoms transfer the energy and are in turn deactivated to their initial energy state. The excited ethylene molecules subsequently undergo decomposition. Another mode of photosensitization observed in many reactions involves direct participation of the sensitizer in the reaction itself.

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Universalium. 2010.

Look at other dictionaries:

  • photosensitization — (Amer.) n. process of photosensitizing; (Dermatology) state of being photosensitized, sensitization of the skin to sunlight; (Medicine) development of irregularly high reactiveness of the eyes to sunlight (also photosensitisation) …   English contemporary dictionary

  • photosensitization — fotosensibilizavimas statusas T sritis chemija apibrėžtis Jautrumo šviesai didinimas. atitikmenys: angl. photosensitization rus. фотосенсибилизация …   Chemijos terminų aiškinamasis žodynas

  • photosensitization — noun Date: circa 1923 1. the process of photosensitizing 2. the condition of being photosensitized; especially the development of an abnormal capacity to react to sunlight typically by edematous swelling and dermatitis …   New Collegiate Dictionary

  • photosensitization — noun a) The acquisition of photosensitivity b) The transfer of a photon from one excited state to another, which then undergoes a reaction …   Wiktionary

  • photosensitization — 1. Sensitization of the skin to light, usually due to the action of certain drugs, plants, or other substances; may occur shortly after administration of the drug (phototoxic sensitivity), or may occur only after a latent period of from days to… …   Medical dictionary

  • photosensitization — pho·to·sensitization …   English syllables

  • photosensitization — “+ noun Etymology: phot + sensitization 1. : the process of photosensitizing 2. : the condition of a cell, tissue, or organism acted upon by a substance (as a dyestuff) that renders it sensitive to a particular region of the spectrum to which it… …   Useful english dictionary

  • hepatogenous photosensitization — photosensitization caused by accumulation in body tissues of a photosensitizing substance, usually because of inadequate clearance through the liver; it often occurs in ruminants when plants break down in the stomach under anaerobic conditions… …   Medical dictionary

  • photosensitize — photosensitization, n. /foh teuh sen si tuyz /, v.t., photosensitized, photosensitizing. to make (a material) photosensitive, as by the application of a photosensitive emulsion. Also, esp. Brit., photosensitise. [1920 25; PHOTOSENSIT(IVE) + IZE]… …   Universalium

  • blue nose disease — photosensitization of the face of a horse following ingestion of any of certain meadow plants; characteristics include blue discoloration of the muzzle, sloughing of nonpigmented skin, and frequently intense excitement …   Medical dictionary


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