Phosphorescence is a type of photoluminescence where a material absorbs energy from a light source (such as sunlight or UV light) and then emits light at a slower rate, even after the light source has been removed. The emitted light often has a longer wavelength than the absorbed light, causing a characteristic glow-in-the-dark effect.
- Here is a short explanation:
- Excitation: When a phosphorescent material is exposed to light, electrons within the material absorb the photons’ energy and move to a higher energy state (become excited).
- Trapped State: Unlike fluorescence, where electrons immediately return to their ground state and emit light, in phosphorescence, the excited electrons get “trapped” in a forbidden triplet state. This means they can’t directly transition back to their lower energy state.
- Gradual Release: Over time, the trapped electrons slowly find their way back to the ground state, releasing the stored energy as light. This process is much slower than fluorescence, which is why phosphorescence produces that lingering afterglow.