IUPAC - photon exitance (P04631)

photon exitance, $M_{p}$

Also contains definition of: specific photon emission

Synonym: photon emittance

https://doi.org/10.1351/goldbook.P04631

Photon flux, number basis,

q_{p}

, emitted by an element of the surface containing the source point under consideration divided by the area

S

of that element. SI unit is

s^{- 1} m^{- 2}

Notes:

Mathematical definition: $d q_{p} / d S$ . If $q_{p}$ is constant over the surface area considered, $M_{p} = q_{p} / S$ .
Formerly called photon emittance.
This quantity can be expressed on a chemical amount basis by dividing $M_{p}$ by the Avogadro constant. In this case the symbol is $M_{n,p}$ , the name 'photon exitance, amount basis', SI unit is $mol s^{- 1} m^{- 2}$ ; common unit is ${einstein s}^{- 1} m^{- 2}$ .

Source:
PAC, 2007, 79, 293. (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 394 [Terms] [Paper]

Citation: 'photon 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.P04631 RIS BibTex EndNote

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Last revised: February 24, 2014

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photon exitance, $M_{p}$

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photon exitance, Mp

photon exitance, $M_{p}$