fosforescenci

Fosforescenci is a type of photoluminescence, a process where a substance absorbs light or other electromagnetic radiation and then re-emits it over a longer period of time. Unlike fluorescence, which ceases almost immediately after the excitation source is removed, phosphorescent materials continue to glow in the dark for minutes, hours, or even days. This sustained emission is due to a phenomenon called intersystem crossing.

When a phosphorescent material absorbs energy, its electrons are excited to a higher energy state. In fluorescence, these electrons quickly return to their ground state, releasing energy as light. However, in phosphorescence, some excited electrons transition to a "triplet state," which is a metastable state. From this triplet state, it is more difficult for electrons to return to the ground state, so they remain trapped for a longer duration, gradually releasing their stored energy as visible light.

Common phosphorescent materials include zinc sulfide and strontium aluminate. These substances are often used in applications where a light source is needed in darkness, such as glow-in-the-dark toys, watch dials, safety signage, and emergency exit markers. The intensity and duration of the glow depend on the specific material and the amount of energy it has absorbed. The process is not a chemical reaction, and the material does not degrade with repeated cycles of absorption and emission.