molar absorption coefficient, ε

also contains definition of: molar decadic absorption coefficient
https://doi.org/10.1351/goldbook.M03972
Absorbance divided by the absorption pathlength, l, and the amount concentration, c: ε(λ)=1cllg(Pλ0Pλ)=A(λ)cl where Pλ0 and Pλ are, respectively, the incident and transmitted spectral radiant power.
Notes:
  1. The term molar absorptivity for molar absorption coefficient should be avoided.
  2. In common usage for l/cm and c/moldm−3 (M), ε(λ) results in dm3mol−1cm−1 (M−1 cm−1, the most commonly used unit), which equals 0.1 m2mol−1 (coherent SI units).
Source:
PAC, 2007, 79, 293. (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 371 [Terms] [Paper]
Citation: 'molar absorption coefficient' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.M03972 RIS BibTex EndNote
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