Phosphorescence (Gr. Phos - Light, Forein - Carry)
Phosphorescence is the emission of light by a substance in a triplet excited state.
Phosphorescence is the emission of light without appreciable generation of heat. This is due to the transition of molecules from the triplet excited state to the ground unexcited state.
Unlike fluorescence, where emission occurs due to the transition of molecules from a singlet excited state, in phosphorescence the transition occurs between the triplet and ground states.
Since the probability of such a transition is low, the decay time of phosphorescence is much longer than that of fluorescence and can reach seconds and minutes. This property is used in the creation of luminous paints and materials.