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radiant power, P

Power emitted, transferred or received as radiation. SI unit is J s −1 = W.
  1. Mathematical definition: P = d Q / d t. If the radiant energy Q is constant over the time interval, P = Q / t.
  2. In radiometry, flux (Φ) is used with the same units as P. The symbol Φ is reserved for quantum yield in photochemistry. Therefore, the use of flux (Φ) is not recommended.
PAC, 2007, 79, 293 (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 410
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IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. doi:10.1351/goldbook.
Last update: 2014-02-24; version: 2.3.3.
DOI of this term: doi:10.1351/goldbook.R05046.
Original PDF version: http://www.iupac.org/goldbook/R05046.pdf. The PDF version is out of date and is provided for reference purposes only. For some entries, the PDF version may be unavailable.
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