radiant exitance, M 

Synonym: radiant emittance
https://doi.org/10.1351/goldbook.R05041
Radiant power, P, emitted at all wavelengths by an element of surface containing the source point under consideration divided by the area of the source. SI unit is W m−2.
Notes:
  1. Mathematical definition: M=dP/dS. If the radiant power P is constant over the surface area considered, M=P/S.
  2. Equivalent to the integration of the radiant power leaving a source over the solid angle and over the whole wavelength range. Mathematical definition: M=∫λMλdλ, where Mλ is the spectral radiant exitance at wavelength λ.
  3. Same as spherical radiant exitance. Formerly called radiant emittance.
Source:
PAC, 2007, 79, 293. (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 409 [Terms] [Paper]
Citation: 'radiant exitance' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.R05041 RIS BibTex EndNote
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Last revised: February 24, 2014