Final answer:
Phosphorescence is the process of phosphors giving off light or glow, while fluorescence occurs when an electron in an atom is excited and de-excites by emitting a photon. Phosphorescence typically takes longer due to the longer lifetimes of the higher energy states involved.
Step-by-step explanation:
The process of phosphors giving off light or glow is known as phosphorescence. Phosphorescence is the de-excitation of a metastable state, where the atoms or molecules are excited to higher levels and decay slowly, releasing the stored excitation energy partially as visible light. In contrast, fluorescence occurs when an electron in an atom is excited by absorbing a photon and de-excites by emitting a photon of lower energy.
Phosphorescence typically takes longer than fluorescence because the higher energy states involved in phosphorescence have longer lifetimes. These energy levels are termed metastable, meaning relatively stable. The longer lifetime allows for a delayed release of the stored excitation energy, resulting in a glow that persists after the excitation source is removed.