Singlet-triplet absorption

{
  "id": "MLC-T-CHM-010906",
  "term": "Singlet-triplet absorption",
  "field": "Chemistry",
  "definition": "The process where a molecule in its ground electronic singlet state absorbs a photon and transitions to an excited electronic triplet state. This transition involves a change in spin multiplicity, making it formally spin-forbidden and therefore much weaker than singlet-singlet absorption. It is often observed in molecules containing heavy atoms or in the presence of paramagnetic species.",
  "subject": "Analytical Chemistry",
  "see_also": [
    "absorption",
    "absorption spectrum",
    "ground state"
  ],
  "references": [
    "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)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/singlet-triplet-absorption/"
}