04314 IUPAC Gold Book - optical spectroscopy 10.1351/goldbook.O04314 O04314 current 1 The study of systems by the electromagnetic radiation with which they interact or that they produce. By convention, spectroscopic properties are expressed in terms of wavelength in vacuo, not the wavelength within the medium being studied. wavelength https://goldbook.iupac.org//terms/view/W06659 PAC, 1985, 57, 105. 'Names, symbols, definitions and units of quantities in optical spectroscopy (Recommendations 1984)' on page 107 (https://doi.org/10.1351/pac198557010105) https://goldbook.iupac.org/terms/view/O04314/html https://goldbook.iupac.org/terms/view/O04314/json https://goldbook.iupac.org/terms/view/O04314/plain Citation: 'optical 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.O04314 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. 2026-06-20T04:41:53+00:00