Phosphorescente

Phosphorescente refers to a property of certain materials to emit light after being excited by external radiation. This phenomenon, known as phosphorescence, is a type of photoluminescence that persists well after the stimulating light source is removed, unlike fluorescence, which ceases almost immediately when excitation ends. The afterglow can last from seconds to hours, depending on the material and conditions.

The persistence of phosphorescence arises when excited electrons become trapped in metastable states or defects within the crystal lattice. These trapped electrons are released slowly over time, emitting photons as they return to the ground state. The duration and intensity of the afterglow depend on the host material, dopants, trap depths, and temperature; higher temperatures generally accelerate decay, while certain dopants can prolong it.

Common phosphorescent materials include inorganic phosphors such as zinc sulfide doped with copper (ZnS:Cu) and strontium aluminate doped with europium and dysprosium (SrAl2O4:Eu2+,Dy3+). These compounds can produce bright afterglows for extended periods and are widely used in glow-in-the-dark applications. Organic and polymer-based phosphorescent systems also exist but are typically less durable for long-lasting afterglow.

Applications of phosphorescent materials include glow-in-the-dark safety signs, luminous watch and instrument dials, decorative items, toys, and emergency markings that provide light without an external power source after prior charging by light. The study of phosphorescence continues to focus on improving efficiency, afterglow duration, and safety of the materials.