Generally used to describe a chemical reaction caused by absorption of ultraviolet
radiation. There are many ground-state reactions,
which have photochemical counterparts. Among these are photochemical nitrogen extrusions,
photocycloadditions, photodecarbonylations, photodecarboxylations, photoenolizations,
, photoisomerizations, photooxidations, photorearrangements,
photoreductions, photosubstitutions, etc.
Photochemical paths offer the advantage over thermal methods of forming
thermodynamically disfavoured products, overcome large activation
barriers in a short
period of time, and allow reactivity otherwise inaccessible by thermal methods.
PAC, 2007, 79, 293
(Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006))
on page 386
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. doi:10.1351/goldbook