{"term":{"id":"01854","title":"double-wavelength spectroscopy","longtitle":"IUPAC Gold Book - double-wavelength spectroscopy","doi":"10.1351\/goldbook.D01854","code":"D01854","status":"current","definitions":[{"id":1,"text":"The effect of spectral background due to impurities, solvent or radiation scattering may be reduced if the difference in the absorbances of a sample measured at two selected wavelengths is obtained. This is often achieved by repetitively switching from one wavelength to the other. Double-wavelength spectroscopy does this automatically by allowing two beams of radiation of different wavelengths to pass through the cell. One beam is fixed at a longer wavelength and the other measures absorbance while being scanned over a limited wavelength range at shorter wavelengths.","links":[{"term":"absorbance","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/A00028"},{"term":"scattering","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/S05487"},{"term":"spectroscopy","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/S05848"},{"term":"wavelength","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/W06659"}],"sources":["PAC, 1988, 60, 1449. 'Nomenclature, symbols, units and their usage in spectrochemical analysis - VII. Molecular absorption spectroscopy, ultraviolet and visible (UV\/VIS) (Recommendations 1988)' on page 1455 (https:\/\/doi.org\/10.1351\/pac198860091449)"]}],"altoutputs":{"html":"https:\/\/goldbook.iupac.org\/terms\/view\/D01854\/html","xml":"https:\/\/goldbook.iupac.org\/terms\/view\/D01854\/xml","plain":"https:\/\/goldbook.iupac.org\/terms\/view\/D01854\/plain"},"citation":"Citation: 'double-wavelength spectroscopy' 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.D01854","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":"2026-04-18T04:52:02+00:00"}}