Spin conservation rule

{
  "id": "MLC-T-CHM-011197",
  "term": "Spin conservation rule",
  "field": "Chemistry",
  "definition": "A principle stating that the total spin angular momentum of a system must remain unchanged during a chemical reaction or physical process. This rule governs the allowed transitions between electronic states in molecules. For example, transitions between singlet and triplet states are spin-forbidden, leading to longer lifetimes for triplet states.",
  "synonyms": [
    "Wigner rule"
  ],
  "subject": "Organic and Biomolecular Chemistry",
  "references": [
    "Orange Book, 2nd ed., p. 185 (https://media.iupac.org/publications/analytical_compendium/)",
    "PAC, 1984, 56, 231. 'Nomenclature, symbols, units and their usage in spectrochemical analysis-Part VI: molecular luminescence spectroscopy' on page 234 (https://doi.org/10.1351/pac198456020231)",
    "PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2277 (https://doi.org/10.1351/pac199668122223)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/spin-conservation-rule/"
}