In asymmetric photochemistry (also called photochirogenesis) light is used to synthesise asymmetric molecules. Circularly polarized light is chiral and processes like circular dichroism exploit the difference in absorption of UV radiation between two optical isomers. All the more reason chemists have been exploring asymmetric photochemistry for over 80 years.

The main methods (For reviews: Feringa et al. 1998 DOI Inoue 1992 DOI) are:
* photodestruction, the conversion of one enantiomer leading to the enrichment of the other enantiomer. Also called asymmetric photolysis.
* Photoresolution, a deracemization process of photochemically interconvertable enantiomers.
* Asymmetric photosynthesis, an enantioselective photochemical formation of an optically active compound from a prochiral substrate. Also called absolute asymmetric synthesis.
* Asymmetric photosensitization with an optically active compound