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radiant intensity, I

Also contains definition of: intensity

Radiant power, P, at all wavelengths per solid angle, Ω. The radiant power emitted in a given direction by a source or an element of the source in a small cone containing the given direction divided by the solid angle of the cone. SI unit is W sr −1.
  1. Mathematical definition: I = d P / d Ω. If the radiant power is constant over the solid angle considered, I = P / Ω.
  2. Equivalent to I = ∫ λ I λ ⁢ d λ, where I λ is the spectral radiant intensity at wavelength λ.
  3. It is not recommended to abbreviate this term to just intensity because it is confusing.
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.R05045.
Original PDF version: http://www.iupac.org/goldbook/R05045.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 The PDF version is out of date and is provided for reference purposes only.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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