Title: Kubelka–Munk function
Long Title: IUPAC Gold Book - Kubelka–Munk function
DOI: 10.1351/goldbook.08631
Status: current

Definition
\(f(R_{\infty}) = (1 – R_{\infty})^{2}/2R_{\infty}\), where \(R_{\infty}\) is the diffuse reflectance from a sample of infinite depth.


Note
Theoretically \(f(R_{\infty})\) equals the ratio of the linear decadic absorption coefficient to the scattering coefficient. Under the assumptions of the Kubelka Munk theory, if the scattering coefficient at a given wavenumber is a constant for a given set of samples, \(f(R_{\infty})\) is directly proportional to the product of the absorption coefficient and concentration of each component of a mixture, analogous to the behaviour of absorbance under Beer’s law.

Related Terms
- diffuse reflectance: https://goldbook.iupac.org//terms/view/08235
- scattering coefficient: https://goldbook.iupac.org//terms/view/16251
- volume reflection: https://goldbook.iupac.org//terms/view/08710
- wavenumber: https://goldbook.iupac.org//terms/view/08302

Source
- PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 753 (https://doi.org/10.1515/pac-2019-0203)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/08631/html
- json: https://goldbook.iupac.org/terms/view/08631/json
- xml: https://goldbook.iupac.org/terms/view/08631/xml

Citation: Citation: 'Kubelka–Munk function' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.08631
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Accessed: 2026-07-27T23:36:19+00:00