Heavy atom effect

{
  "id": "MLC-T-CHM-005150",
  "term": "Heavy atom effect",
  "field": "Chemistry",
  "definition": "An increase in the rate of intersystem crossing (ISC) and phosphorescence in a molecule when a heavy atom, either internal to the molecule or in the solvent, is present. This effect arises from enhanced spin-orbit coupling, which facilitates transitions between states of different spin multiplicity. The efficiency of this effect generally increases with the atomic number of the heavy atom.",
  "synonyms": [
    "external heavy atom effect"
  ],
  "subject": "Organic and Biomolecular Chemistry",
  "see_also": [
    "atomic number",
    "spin-orbit coupling"
  ],
  "references": [
    "PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2245 (https://doi.org/10.1351/pac199668122223)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/heavy-atom-effect/"
}