molar absorption coefficient, $ɛ$

Also contains definition of: molar decadic absorption coefficient

Absorbance divided by the absorption pathlength, $l$ , and the amount concentration, $c$ :

$ɛ λ = 1 c l lg ( P λ 0 P λ ) = A λ c l$

where $P λ 0$ and $P λ$ are, respectively, the incident and transmitted spectral radiant power.

Notes:

The term molar absorptivity for molar absorption coefficient should be avoided.
In common usage for $l / cm$ and $c / mol dm −3$ ( $M$ ), $ɛ λ$ results in $dm 3 mol −1 cm −1$ ( $M −1 cm −1$ , the most commonly used unit), which equals $0.1 m 2 mol −1$ (coherent SI units).

Source:

PAC, 2007, 79, 293 (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 371

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.M03972.

Original PDF version: http://www.iupac.org/goldbook/M03972.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 The PDF version is out of date and is provided for reference purposes only.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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