All of these products take advantage of photochemistry, reactions that occur when matter, or molecules, react with light. Light is a form of energy. The chemical properties of the molecules also change as the molecules fall apart and change their atomic structures or become more reactive.
Photochemical reactions are common in nature.
Photosynthesis, the process by which plants make their own food, is an example of a photochemical reaction that occurs when chlorophyll in plants absorbs light from the sun. The formation of smog in the atmosphere is another common photochemical reaction. Sunlight reacts with atmospheric pollutants such as nitrogen oxides and sulfur dioxide, which fall apart or rearrange themselves and react again to produce ozone, the primary ingredient of smog. The goal of this research is to learn exactly how these reactions proceed and how particular molecules change when they absorb light. This basic knowledge, Laane said, provides insight into how photochemical processes work on a fundamental level and why molecules, normal or excited, have the shapes and structures they do.