Chemiluminescence is distinctly different from fluorescence and phosphorescence, which occur when electrons in a molecule are driven to a higher-energy orbital by the absorption of light energy. Both processes may occur in living organisms. Atoms of a fluorescent material typically emit the absorbed radiation only as long as the atoms are being irradiated (as in a fluorescent lamp). Phosphorescent materials, on the other hand, continue to emit light for a much longer time after the incident radiation is removed (glowing hands on watches and clocks are familiar examples).