Fosforenssissa

Fosforenssissa refers to the phenomenon of phosphorescence, a type of photoluminescence. In phosphorescence, a substance absorbs light energy and then re-emits that energy over a period of time, often minutes or even hours, after the excitation source has been removed. This is distinct from fluorescence, where the emission of light occurs almost instantaneously.

The mechanism behind phosphorescence involves electrons in the material being excited to a higher energy state by absorbing photons. However, instead of immediately returning to their ground state and emitting light, some electrons become trapped in a metastable state. From this metastable state, the electrons slowly return to their ground state, releasing energy in the form of photons. This gradual release of energy is what causes the "glow-in-the-dark" effect seen in many phosphorescent materials.

Common examples of phosphorescent materials include zinc sulfide doped with copper or manganese, and strontium aluminate doped with europium and dysprosium. These materials are used in a variety of applications, such as safety signage, watch dials, and novelty toys, due to their ability to store light and emit it in darkness. The duration and intensity of the glow depend on the specific chemical composition of the phosphorescent substance and the wavelength and intensity of the absorbed light.