07448 IUPAC Gold Book - photochemical reaction path 10.1351/goldbook.PT07448 PT07448 current abbrev: MERP 1 Sequence of geometries adopted by a molecule after initial electronic excitation, combined with a specification of the electronic state at each geometry, from radiation absorption to product formation. Theoretically, this usually involves the computation of the MERP connecting the Franck–Condon point, located on the potential-energy surface of the spectroscopic state, to the final photoproducts located on the ground-state potential-energy surface. Experimentally, a photochemical reaction path can be probed by detecting transient species or reaction intermediates. Sequence https://goldbook.iupac.org//terms/view/ST06775 electronic state https://goldbook.iupac.org//terms/view/ET07026 photochemical reaction https://goldbook.iupac.org//terms/view/P04585 potential-energy surface https://goldbook.iupac.org//terms/view/P04780 PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 386 (https://doi.org/10.1351/pac200779030293) https://goldbook.iupac.org/terms/view/PT07448/html https://goldbook.iupac.org/terms/view/PT07448/json https://goldbook.iupac.org/terms/view/PT07448/plain Citation: 'photochemical reaction path' 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.PT07448 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. 2026-05-18T07:25:27+00:00