Term: radiant exitance, \(M\)
https://doi.org/10.1351/goldbook.R05041

Definition:
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:
0) Mathematical definition: M = dP/dS. If the @R05046-2@ P is constant over the surface area considered, M = P/S.
1) Equivalent to the integration of the @R05046-3@ leaving a source over the solid @A00346@ and over the whole @W06659@ range. Mathematical definition: M = ∫(λ).Mλ.⁢dλ, where M λ is the @S05825@ at @W06659@ λ.
2) Same as spherical radiant @E02264@. Formerly called radiant emittance.

Related Terms:
1) radiant power (http://doi.org/10.1351/goldbook.R05046-2).
2) radiant power (http://doi.org/10.1351/goldbook.R05046-3).
3) angle (http://doi.org/10.1351/goldbook.A00346).
4) wavelength (http://doi.org/10.1351/goldbook.W06659).
5) spectral radiant exitance (http://doi.org/10.1351/goldbook.S05825).
6) exitance (http://doi.org/10.1351/goldbook.E02264).
7) radiant power (http://doi.org/10.1351/goldbook.R05046-1).

Source: PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 409 (https://doi.org/10.1351/pac200779030293)

Citation: 'radiant exitance, \(M\)' 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

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