In some applications it is useful to consider electronic excitation as if a quasi-particle,
capable of migrating, were involved. This is termed an exciton. In organic materials
two models are used: the band or wave model (low temperature, high crystalline order)
and the hopping model (higher temperature, low crystalline order or amorphous state).
Energy transfer in the hopping limit is identical with energy migration
PAC, 1996, 68, 2223
(Glossary of terms used in photochemistry (IUPAC Recommendations 1996))
on page 2241
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by
A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997).
XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic,
J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. https://doi.org/10.1351/goldbook