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(analytical chemistry)
The constant a in the Beer's law relation A = abc, where A is the absorbance, b the path length, and c the concentration of solution. Also known as absorptive power. Formerly known as absorbency index; absorption constant; extinction coefficient.
The ratio of the radiation absorbed by a surface to the total radiation incident on the surface.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



(or absorptive power), αv, the fraction of a monochromatic radiation flux of frequency v that is absorbed by a body on which the flux is incident. Although often called the absorption factor, it differs from the absorption factor in that it applies only to radiation of a specific frequency. The absorption factor is the integral of the absorptivities over all the frequencies present in the irradiating flux. The absorptivity for thermal radiation is dependent not only on the frequency or wavelength of the radiation but also on the temperature T of the body:

α = α(ν, T) = α*(λ, T)


Landsberg, G. S. Optika, 4th ed. Moscow, 1957. (Obshchii kurs fiziki, vol. 3.)
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
The absorbance components of the spectra in the wavelength which range from 250 to 300 nm are further analyzed based on the Beer-Lambert Law; the compositional information on nucleic acid and protein content can be obtained, which agrees with literature values reported for E.
In this section, the validation of the microchannel experimental results was done by comparing with UV spectrophotometer reading and also with theoretical calculation using Beer-Lambert Law of Absorption.
As can be seen from the proof procedure of the Beer-Lambert Law, transmittance is derived from the equation below:
The measured gas type, its absorption coefficient, and the gas concentration range all impact the amount of incident light on the thermopile detector, as dictated by the previously discussed Beer-Lambert law. Thermopiles used as IR detectors in NDER systems produce a voltage (V) based on the amount of incident light they receive in Watts (W).
The Beer-Lambert law is the mathematical principle used to describe light absorption and the properties of the material through which the light is traveling.