Intersystem crossing

Intersystem crossing (ISC) is an isoenergetic radiationless process involving a transition between the two electronic states with different spin multiplicity.[1]

Excited electrons can undergo intersystem crossing to a degenerate state with a different spin multiplicity.
  1. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "Intersystem crossing". doi:10.1351/goldbook.I03123