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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.
  1. The term molar absorptivity for molar absorption coefficient should be avoided.
  2. 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).
PAC, 2007, 79, 293 (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 371
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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: (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8.
Last update: 2014-02-24; version: 2.3.3.
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