Phosphorescence Definition

Plastic stars glow in the dark from phosphorescence.
Plastic stars glow in the dark from phosphorescence. shaunl / Getty Images

Phosphorescence Definition

Phosphorescence is luminescence that occurs when energy is supplied by electromagnetic radiation, usually ultraviolet light. The energy source kicks an electron of an atom from a lower energy state into an "excited" higher energy state; then the electron releases the energy in the form of light (luminescence) when it falls back to a lower energy state.

Phosphorescence releases the stored energy slowly over time. When the energy is released immediately after absorbing the incident energy, the process is called fluorescence.

Examples of Phosphorescence

Common examples of phoshorescence include stars people put on bedroom walls that glow for hours after the lights are turned out and paint used to make glowing star murals. Although the element phosphorus glows green, this is oxidation and not an example of phosphorescence.