The movement of electronic
excitation energy from one molecular entity to another of the same species, or from one part of a molecular entity to another of the same kind (e.g. excitation
migration between the chromophores of an aromatic polymer). The
migration can happen via radiative or radiationless processes.
Source:
PAC, 1996, 68, 2223
(Glossary of terms used in photochemistry (IUPAC Recommendations 1996))
on page 2238