08550 IUPAC Gold Book - spectral line 10.1351/goldbook.08550 08550 current synonyms: line, spectral line 1 In atomic spectroscopy, a very narrow band of frequencies of electromagnetic radiation emitted or absorbed by atoms, which undergo a single electronic transition. The radiation is centred on a peak whose wavelength characterizes the line and which corresponds to the emission or absorption maximum. A distinction is made between lines corresponding to transition of neutral atoms (e.g., \(\ce{Ba I}\ \pu{553.548 nm}\) and \(\pu{577.762 nm}\)) and ions (e.g., \(\ce{Ba II}\ \pu{455.403 nm}\)). atomic spectroscopy https://goldbook.iupac.org//terms/view/08216 electromagnetic radiation https://goldbook.iupac.org//terms/view/08242 electronic transition https://goldbook.iupac.org//terms/view/08245 wavelength https://goldbook.iupac.org//terms/view/08300 PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 734 (https://doi.org/10.1515/pac-2019-0203) https://goldbook.iupac.org/terms/view/08550/html https://goldbook.iupac.org/terms/view/08550/json https://goldbook.iupac.org/terms/view/08550/plain Citation: 'spectral line' 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.08550 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. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . 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. 2026-05-30T23:25:28+00:00