radiant exposure, $H$

Radiant energy, $Q$ , incident from all upward directions on an small sphere divided by the cross-sectional area of that sphere. SI unit is $J m −2$ .

Notes:

Equivalent definition: Irradiance, $E,$ integrated over the time of irradiation.
Mathematical definition: $H = d Q / d S = ∫ t E ⁢ d t$ If $Q$ is constant over the area, $H = Q / S$ . If $E,$ is constant over the time interval, $H = E t$ .
This term refers to a beam not scattered or reflected by the target or its surroundings. For a beam incident from all directions fluence ( $H o$ , $F o$ ) is an equivalent term.

Source:

PAC, 2007, 79, 293 (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 409

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.R05042.

Original PDF version: http://www.iupac.org/goldbook/R05042.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 The PDF version is out of date and is provided for reference purposes only.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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