spectral line 

of an atom
Synonyms: line, spectral line
https://doi.org/10.1351/goldbook.08550
In atomic spectroscopy, a very narrow band of frequencies of electromagnetic radiation emitted or absorbed by atoms, which undergo a single electronic transition.
Notes:
  1. The radiation is centred on a peak whose wavelength characterizes the line and which corresponds to the emission or absorption maximum.
  2. A distinction is made between lines corresponding to transition of neutral atoms (e.g., Ba I 553.548 nm and 577.762 nm) and ions (e.g., Ba II 455.403 nm).
Source:
PAC, 2021, 93, 647. (Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)) on page 734 [Terms] [Paper]
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. https://doi.org/10.1351/goldbook.08550 RIS BibTex EndNote
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