actinometer


actinometer
actinometric /ak tin'oh me"trik, ak'teuh noh-/, actinometrical, adj.actinometry, n.
/ak'teuh nom"i teuhr/, n.
a device for measuring intensity of radiation, esp. that of the sun. Cf. actinograph.
[1825-35; ACTINO- + -METER]

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      in chemistry, a substance or a mixture of substances that reacts through the action of light and that, because of the easily determined quantitative relationship between the extent of the reaction and the energy of the absorbed light, is used as a standard for measurement of light energies involved in photochemical work.

      A typical actinometer is a liquid solution of oxalic acid containing uranyl sulfate. Light in the wavelength range of about 2,080 to 4,350 angstroms (ultraviolet to violet light) decomposes the oxalic acid (through a complex process involving initial absorption of the light energy by the uranyl ion) into a mixture of carbon dioxide, carbon monoxide, and water. A standard solution is generally irradiated with light of the proper wavelength and of known intensity, and the quantity of oxalic acid decomposed is accurately measured by titration with potassium permanganate. The experimentally determined relationship between the quantity of oxalic acid transformed and the quantity of light energy absorbed can then be used as a scale from which to predict either quantity when the other is known or measured.

      In addition to the oxalic acid–uranyl sulfate solution, other substances commonly used as chemical actinometers include acetone, hydrogen bromide, carbon dioxide, and a solution of ferrioxalate in sulfuric acid.

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Universalium. 2010.

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  • Actinometer — Ac ti*nom e*ter, n. [Gr. ?, ?, ray + meter] (a) An instrument for measuring the direct heating power of the sun s rays. (b) An instrument for measuring the actinic effect of rays of light. [1913 Webster] …   The Collaborative International Dictionary of English

  • actinometer — [ak΄tə näm′ət ər] n. 1. Physics an instrument for measuring the intensity of the sun s rays, or the actinic effect of light rays 2. Photog. EXPOSURE METER actinometric [ak΄tənō΄me′trik] adj. actinometry [ak΄tənäm′ə trē] n …   English World dictionary

  • Actinometer — Actinometers are instruments used to measure the heating power of radiation. They are used in meteorology to measure solar radiation as pyrheliometers.An actinometer is a chemical system or physical device which determines the number ofphotons in …   Wikipedia

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  • actinometer — noun Date: 1833 any of various instruments for measuring the intensity of incident radiation; especially one in which the intensity of radiation is measured by the speed of a photochemical reaction • actinometric adjective • actinometry noun …   New Collegiate Dictionary

  • actinometer — noun A device used to measure the heating power of electromagnetic radiation, especially that of solar radiation See Also: actinometric, actinometry …   Wiktionary

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  • actinometer — ac·ti·nom·e·ter .ak tə näm ət ər n any of various instruments for measuring the intensity of incident radiation esp one in which the intensity of radiation is measured by the speed of a photochemical reaction ac·ti·no·me·tric nō me trik adj… …   Medical dictionary

  • actinometer — instrument for measuring incident radiation Scientific Instruments …   Phrontistery dictionary