Definition - What does Photochemical Reaction mean?
A photochemical reaction is a chemical reaction that is initiated when the molecules of a substance absorb light energy. This reaction causes the molecules to undergo a transient excited state, consequently changing their physical and chemical properties from the original molecule of the substance. When this occurs, these molecules tend to form a new structure, or combine with each other or other molecules, and transfer electrons, atoms, protons or other excitation energy to other molecules, thus causing a prolonged chemical chain reaction.
Corrosionpedia explains Photochemical Reaction
Photochemical reactions are related to a branch of chemistry known as photochemistry, which is concerned with the chemical effects of light.
A common example of a photochemical process is plant photosynthesis.