The capacity of a material to absorb incident radiant energy. A special case of absorptance, it is a fundamental property of material that has a specular (optically smooth) surface and is sufficiently thick to be opaque. It may be further qualified as spectral absorptivity Absorptivity-emissivity ratio: The ratio of absorptivity of solar radiation to infrared emissivity of a material.

The capacity of a material to absorb incident radiant energy, measured as the ratio of the amount of radiant energy absorbed to the total amount incident on the material.

The ratio of absorbed radiation by an object to the absorbed radiation by a black body at the same wavelength and temperature.

Ratio of the absorbed to incident electromagnetic radiation on a surface.

Percentage of infrared energy amount absorbed by a substrate, as compared with total amount of incident infrared energy.

the property of a body that determines the fraction of incident radiation absorbed by the body.

acceptance by a body of incident radiation resulting in its temperature rising. It is usually taken to be numerically equivalent to emissivity (q.v.) for the given wavelength.

In a solar thermal system, the ratio of solar energy striking the absorber that is absorbed by the absorber to that of solar energy striking a black body (perfect absorber) at the same temperature. The absorptivity of a material is numerically equal to its emissivity.

(a) extinction coefficient; absorption cross section; decadic absorptivity. Compare with molar absorptivity and absorbance. The absorbance of a solution per unit of path length and per unit concentration; a = A/(bc) where a, A, b, and c are the absorptivity, absorbance, path length, and concentration, respectively. Absorptivity varies with wavelength of the incident light.

A property of a material, characterizing its capability to absorb rather than transmit or reflect incident radiant energy.

also known as the molar extinction coefficient in molecular spectroscopy, it is the wavelength-dependent absorption of an analyte as a function of concentration and pathlength and is expressed in units of concentration -1 * cm -1.