Extinction coefficient
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Extinction coefficient refers to several different measures of the absorption of light in a medium:
- In chemistry, the molar absorptivity, the mass extinction coefficient or the molar extinction coefficient are all similar parameters defining how strongly a chemical species absorbs light at a given wavelength, per mole, per mass or per concentration.
- In physics, the extinction coefficient is the imaginary part of the complex index of refraction, which also relates to light absorption.
(For the relation between the chemistry and physics definitions, see Mathematical descriptions of opacity.)