Kasha rule

{
  "id": "MLC-T-CHM-006307",
  "term": "Kasha rule",
  "field": "Chemistry",
  "definition": "A principle stating that luminescence (fluorescence or phosphorescence) typically occurs from the lowest vibrational level of the lowest excited electronic state of a given multiplicity. This means that regardless of which excited state or vibrational level is initially populated, rapid internal conversion and vibrational relaxation lead to emission from the lowest excited state. The rule applies to most organic molecules in solution.",
  "subject": "Organic and Biomolecular Chemistry",
  "see_also": [
    "excited state",
    "molecular entity"
  ],
  "references": [
    "PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 360 (https://doi.org/10.1351/pac200779030293)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/kasha-rule/"
}