extinction

The molar absorption coefficient, also known as the molar absorptivity, is a measure of how strongly a chemical species absorbs light at a given wavelength. Quantitatively, it represents the absorbance of a solution containing that species at a concentration of 1 mole per liter, with a path length of 1 centimeter. For example, a substance with a high molar absorption coefficient will absorb a large amount of light even at low concentrations.

This value is a fundamental property of a substance and is crucial in quantitative analysis. Its determination allows for accurate quantification of the substance in various mixtures. Historically, its understanding has been essential in fields ranging from chemistry and biochemistry to environmental science, permitting researchers to identify and quantify compounds in complex samples and understand reaction kinetics.

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Determining the inherent ability of a chemical species to absorb light at a given wavelength is a fundamental task in spectrophotometry. This value, specific to each substance, quantifies the degree to which a solution attenuates light. For example, a solution containing a high concentration of a strongly absorbing molecule will allow very little light to pass through, while a solution containing a lower concentration of a weakly absorbing molecule will allow more light to pass through.

This determination is critical for quantitative analysis in various fields, including chemistry, biology, and environmental science. It facilitates accurate measurements of concentrations using spectroscopic techniques. Historically, this parameter has been vital in elucidating molecular structures and understanding reaction kinetics, enabling researchers to characterize and quantify substances reliably. Furthermore, it provides a benchmark for comparing the light-absorbing properties of different molecules.

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