Fluorescence Definition

Chemistry Glossary Definition of Fluorescence

Fluorescent light
Fluorescent lights are coated with phoshors that absorb energy and release it as visible light. Verena Andrea Philipp / EyeEm / Getty Images
by Anne Marie Helmenstine, Ph.D.
Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels.
Updated July 28, 2018

Fluorescence is luminescence that occurs where the 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.

Fluorescence Examples:

fluorescent lights, the red glow of rubies in sunlight, phosphors in television screens