# Absorptivity

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Related to molar absorption coefficient: Molar extinction coefficient, Beer lambert law

## absorptivity

[əb‚sȯrp′tiv·əd·ē]
(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.
(thermodynamics)
The ratio of the radiation absorbed by a surface to the total radiation incident on the surface.

## Absorptivity

(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)

### REFERENCE

Landsberg, G. S. Optika, 4th ed. Moscow, 1957. (Obshchii kurs fiziki, vol. 3.)
References in periodicals archive ?
An Eppendorf EPOS 5060 analyzer was used for method comparisons, the establishment of reference intervals, and as a spectrometer for the determination of molar absorption coefficients at 405 nm.
We calculated molar absorption coefficients by measuring solutions of 100 [micro]mol/L 4-nitrophenyl and used pH-specific absorbances to correct all data from photometric readings.

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