Measure of how strongly a chemical species absorbs a given wavelength of light
In chemistry, the molar absorption coefficient or molar attenuation coefficient (ε)[1] is a measurement of how strongly a chemical species absorbs, and thereby attenuates, light at a given wavelength. It is an intrinsic property of the species. The SI unit of molar absorption coefficient is the square metre per mole (m2/mol), but in practice, quantities are usually expressed in terms of M−1⋅cm−1 or L⋅mol−1⋅cm−1 (the latter two units are both equal to 0.1 m2/mol). In older literature, the cm2/mol is sometimes used; 1 M−1⋅cm−1 equals 1000 cm2/mol. The molar absorption coefficient is also known as the molar extinction coefficient and molar absorptivity, but the use of these alternative terms has been discouraged by the IUPAC.[2][3]
^"Chapter 11 Section 2 - Terms and symbols used in photochemistry and in light scattering" (PDF). Compendium on Analytical Nomenclature (Orange Book). IUPAC. 2002. p. 28.
^IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "Extinction". doi:10.1351/goldbook.E02293
^IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "Absorptivity". doi:10.1351/goldbook.A00044
and 21 Related for: Molar absorption coefficient information
In chemistry, the molarabsorptioncoefficient or molar attenuation coefficient (ε) is a measurement of how strongly a chemical species absorbs, and thereby...
related concept is molarabsorptivity. They are quantitatively related by (mass attenuation coefficient) × (molar mass) = (molarabsorptivity). Tables of photon...
cross-section is closely related to molarabsorptivity ε {\displaystyle \varepsilon } and mass absorptioncoefficient. σ = ln ( 10 ) × 10 3 N A × ε {\displaystyle...
Extinction coefficient refers to several different measures of the absorption of light in a medium: Attenuation coefficient, sometimes called "extinction...
the attenuation coefficient. The attenuation coefficient of a volume is the sum of absorptioncoefficient and scattering coefficients: μ = μ a + μ s ...
the excitation and emission spectra (usually one peak each). Molarabsorptioncoefficient (in mol−1cm−1): links the quantity of absorbed light, at a given...
electric field changes the molarabsorptioncoefficient of the sample, which can be measured using traditional absorption or emission spectroscopic methods...
the absorbance; ε {\displaystyle \varepsilon } is the molar attenuation coefficient or absorptivity of the attenuating species; ℓ {\displaystyle \ell }...
The absorption peaks of chlorophyll a are at 465 nm and 665 nm. Chlorophyll a fluoresces at 673 nm (maximum) and 726 nm. The peak molarabsorption coefficient...
strain) divided by the change in temperature is called the material's coefficient of linear thermal expansion and generally varies with temperature. As...
transmission coefficient, which is the ratio of the transmitted to incident electric field. Internal transmittance refers to energy loss by absorption, whereas...
attenuation coefficient; see attenuation coefficient for details; molarabsorptioncoefficient or molar extinction coefficient, also called molarabsorptivity, is...
called the optical extinction coefficient or absorptioncoefficient—although κ can also refer to the mass attenuation coefficient: 3 —and indicates the amount...
\varepsilon _{\mathrm {R} }} are the molar extinction coefficients for LCP and RCP light, C {\displaystyle C} is the molar concentration, l {\displaystyle...
which A is the absorbance measured by the instrument, ε is the molarabsorptioncoefficient of the sample, l is the pathlength of the light beam through...
the path length), ℓ. The absorption coefficient can, in turn, be written as a product of either a molarabsorptivity of the absorber, ε, and the concentration...
the absorption spectra of two species (whether by using molarabsorptivity for the representation, or by using absorbance and keeping the same molar concentration...
ammonia per litre of solution, and has a molarity of approximately 18 mol/L. At higher temperatures, the molarity of the saturated solution decreases and...
c of the solute (the solvent is considered non-absorbing). The “AbsorptionCoëfficient” that Beer defined is actually the transmittance (or transmission...
molecule has a logarithm of partition coefficient (log P) between -0.4 and 5.6, molecular weight 160-480 g/mol, molar refractivity of 40–130, which is related...
the cooling system. Compared to mechanical chillers, absorption chillers have a low coefficient of performance, however, it should be taken into consideration...
Global Information