Term: charge-transfer transition to solvent (CTTS) https://doi.org/10.1351/goldbook.C01009 Definition: Electronic transition which is adequately described by single electron transfer between a solute and the solvent, as opposed to excitation followed by electron transfer to solvent. Related Terms: 1) charge-transfer transition (http://doi.org/10.1351/goldbook.C01008). 2) electron transfer (http://doi.org/10.1351/goldbook.E02011). Source: PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2232 (https://doi.org/10.1351/pac199668122223) Citation: 'charge-transfer transition to solvent (CTTS)' 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.C01009 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. 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.