photon exposure, $H p$

Photon irradiance, $E p$ , integrated over the time of irradiation for a beam incident from all upward directions. SI unit is $m −2$ .

Notes:

Mathematical definition: $H p = ∫ t E p ⁢ d t$ . If the photon irradiance is constant over the time interval, $H p = E p t$ .
This term refers to a beam not scattered or reflected by the target or its surroundings. For a beam incident from all directions photon fluence ( $H p , o$ , $F p , o$ ) is an equivalent term.
This quantity can be used on a chemical amount basis by dividing $H p$ by the Avogadro constant, the symbol then being $H n , p$ , the name 'photon exposure, amount basis', SI unit is $mol m −2$ ; common unit is $einstein m −2$ .

Source:

PAC, 2007, 79, 293 (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 394

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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.P04632.

Original PDF version: http://www.iupac.org/goldbook/P04632.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 The PDF version is out of date and is provided for reference purposes only.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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