n.
Emission of light from a substance exposed to radiation and persisting as an afterglow after the exciting radiation has been removed.
Unlike fluorescence , in which the absorbed light is emitted about 10 -8 second after excitation, in phosphorescence the extra energy absorbed is stored in metastable states and reemitted later. Phosphorescence may last from about 10 -3 second to days or even years. The term phosphorescence is often applied to luminescence of living organisms, as well.