photolysis

https://doi.org/10.1351/goldbook.P04624
The cleavage of one or more covalent bonds in a molecular entity resulting from absorption of light, or a photochemical process in which such cleavage is an essential part. For example:
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The term is used incorrectly to describe irradiation of a sample, although in the combination flash photolysis this usage is accepted.
Source:
PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1150 (https://doi.org/10.1351/pac199466051077)