What does photochemistry mean?
Photochemistry is the study of chemical change brought about by light. It examines how molecules absorb light, enter excited states, and either release energy or react with other substances. The field is especially important in photography, photosynthesis, photodynamic treatments, the formation of atmospheric pollutants, and the design of light-sensitive materials. Some processes that are commonly described as photochemical are also studied in closely related disciplines, including photophysics and photobiology. Photochemistry can therefore refer broadly to a scientific field or more narrowly to the set of reactions caused by light. The word is generally technical, though introductory explanations of chemical reactions often use it to emphasize the role of light as a trigger for molecular change.
nounThe branch of chemistry concerned with chemical reactions and processes caused by light. It includes the study of how light is absorbed, how excited molecules behave, and how radiation can initiate or alter chemical change.
- The scientific study of chemical reactions and processes induced by light.
- The chemical reactions or processes themselves when studied in this way.
"The researchers used photochemistry to study how light triggers reactions in atmospheric molecules."
"Advances in photochemistry have improved the efficiency of light-powered chemical manufacturing."
"The experiment illustrates a basic principle of photochemistry: light can initiate a chemical transformation."
The plural is grammatically possible but rarely needed and uncommon in technical writing.
"The laboratory's research programmes encompass several areas of photochemistries."
Photochemistry reveals what happens when light does more than illuminate: it can split molecules, rearrange atoms, and launch entirely new reactions.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does photochemistry come from?
Photochemistry combines Greek phōtos, meaning “light,” with chemistry, which derives from Greek khēmeía, meaning “the art of blending liquids” and ultimately from khimía, associated with alchemy. The combination became established as light gained prominence in the scientific study of chemical reactions. Other English words built on Greek phōtos, including photography and photosynthesis, share the same light-related root.
Related word forms
How photochemistry is actually used
Usually used in scientific and technical contexts. It denotes both the field of study and, less commonly, the light-induced chemical processes examined by that field.