What is an example of a phosphorescence?

Example of Phosphorescence

Zinc Sulfide doped with Copper (ZnS:Cu) is a classic example of a phosphorescent material. When exposed to light, it absorbs photons and subsequently releases them slowly over time, a phenomenon known as phosphorescence.

Explanation

Phosphorescence refers to a specific type of photoluminescence related to the release of energy by certain substances after they have absorbed photons. This process differs from fluorescence, as the energy is released over a longer period - from several minutes to hours or more - after the initial absorption has stopped. This lingering glow is what distinguishes phosphorescence.

In the case of Zinc Sulfide doped with Copper, the copper acts as an activator, enhancing the phosphorescent properties of the base material, Zinc Sulfide. When ZnS:Cu is exposed to ultraviolet light or another form of electromagnetic radiation, electrons in the material absorb energy and jump to higher energy levels. Once the source of the radiation is removed, these electrons return to their ground state over time, releasing the stored energy as visible light. This delayed re-emission of light is what we observe as a glow in the dark.

The practical applications of phosphorescent materials like ZnS:Cu are vast, including emergency signs, watch dials, and novelty items like glow-in-the-dark toys.