One common compound is a mixture of zinc sulfide, copper, and sodium fluroescein.
Light excites electrons within the zinc sulfide, causing it to emit blue-violet light.
This light is absorbed by the sodium fluorescein, which reemits the light as fluorescence. Years ago, companies used radioactive substances to make plastics glow. Such substances have since been abandoned, and today all fluorescent compounds are nontoxic. Due to the large volume of mail we receive only questions for publication can be answered. The official Web site of Popular Science Magazine.