The enhancement of the rate of a spin-forbidden process by the presence of an atom
of high
atomic number, which is either part of, or external to, the excited molecular entity. Mechanistically,
it responds to a
spin-orbit coupling enhancement produced by a heavy atom.
Source:
PAC, 1996, 68, 2223
(Glossary of terms used in photochemistry (IUPAC Recommendations 1996))
on page 2245