{"term":{"id":"08577","title":"Christiansen effect","longtitle":"IUPAC Gold Book - Christiansen effect","doi":"10.1351\/goldbook.08577","code":"08577","status":"current","definitions":[{"id":1,"text":"Collections of solid particles that are transparent to electromagnetic radiation of a particular wavelength and are slightly larger than the wavelength of the radiation transmit poorly due to reflection and scattering from the interfaces. The transmission increases markedly at wavenumbers at which the refractive index of the particles is close to that of the surrounding medium.","notes":{"1":"The Christiansen effect frequently causes strong absorption bands from coarsely ground particles to be distorted due to the change in refractive index associated with the anomalous dispersion of the refractive index through the absorption region."},"links":[{"term":"electromagnetic radiation","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/08242"},{"term":"reflection","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/08281"},{"term":"wavelength","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/08300"}],"sources":["PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 740 (https:\/\/doi.org\/10.1515\/pac-2019-0203)"]}],"altoutputs":{"html":"https:\/\/goldbook.iupac.org\/terms\/view\/08577\/html","xml":"https:\/\/goldbook.iupac.org\/terms\/view\/08577\/xml","plain":"https:\/\/goldbook.iupac.org\/terms\/view\/08577\/plain"},"citation":"Citation: 'Christiansen effect' 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.08577","license":"The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/) for individual terms.","collection":"If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org .","disclaimer":"The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.","accessed":"2026-08-04T00:22:59+00:00"}}