{"term":{"id":"00502","title":"atomic spectral lines","longtitle":"IUPAC Gold Book - atomic spectral lines","doi":"10.1351\/goldbook.A00502","code":"A00502","status":"current","also defines":"<em>also defines<\/em>: ionic spectral lines","definitions":[{"id":1,"text":"Atomic and ionic spectral lines originate from specified electronic transitions between energy levels of atoms and ions, respectively. In the past it has been common usage to denote atomic lines as arc lines and ionic lines as spark lines. This usage is now considered to be incorrect. The correct way to indicate that lines are due to atomic or ionic transitions is: Element symbol I wavelength, e.g., Cu I \\(324.7\\ \\rm{nm}\\); and Element symbol II wavelength, e.g., Cu II \\(213.6\\ \\rm{nm}\\). Similarly for higher states of ionization, the type of line is represented by III, IV, etc.","links":[{"term":"ionization","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/I03183"},{"term":"wavelength","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/W06659"}],"sources":["Orange Book, 2nd ed., p. 118 (https:\/\/media.iupac.org\/publications\/analytical_compendium\/)"]}],"altoutputs":{"html":"https:\/\/goldbook.iupac.org\/terms\/view\/A00502\/html","xml":"https:\/\/goldbook.iupac.org\/terms\/view\/A00502\/xml","plain":"https:\/\/goldbook.iupac.org\/terms\/view\/A00502\/plain"},"citation":"Citation: 'atomic spectral lines' 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.A00502","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":"2026-05-01T11:59:46+00:00"}}