photon flux, $q p$ , $Φ p$

Number of photons (quanta of radiation, $N p$ ) per time interval. SI unit is $s −1$ .

Notes:

Mathematical definition: $q p = d N p / d t$ . If the number of photons is constant over the time interval, $q p = N p / t$ .
This quantity can be used on a chemical amount basis by dividing the photon flux, number basis, $q p$ , by the Avogadro constant, the symbol then being $q n , p$ , the name 'photon flux, amount basis', SI unit is $mol s −1$ ; common unit is $einstein s −1$ .
Although the symbol recommended by CEI is $Φ p$ , the symbol $q p$ is preferred since $Φ$ is reserved for quantum yield.

Source:

PAC, 2007, 79, 293 (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 395

Related index:

IUPAC > Gold Book > math/physics > quantities

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Cite as:
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. https://doi.org/10.1351/goldbook.

Last update: 2014-02-24; version: 2.3.3.

DOI of this term: https://doi.org/10.1351/goldbook.P04636.

Original PDF version: http://www.iupac.org/goldbook/P04636.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 The PDF version is out of date and is provided for reference purposes only.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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photon flux, $q p$ , $Φ p$