Preparation of glow in the dark powder (Zinc Sulfide)
name: Phosphorescent zinc sulfide prepared by oxidation of zinc with sulfur
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Zinc is an easily oxidized metal. Despite the fact that sulfur is a weak oxidizing agent, the reaction between zinc and sulfur proceeds. However, activation is required for this process.
Zinc sulfide is one of the most common phosphorescent materials.
Phosphorescence is a special type of photoluminescence. Unlike fluorescent substance, a phosphorescent material emits absorbed energy at once. More time for re-emission is due to the banned by energy transitions in quantum mechanics. Due to the fact that these transitions occur rarely in the conventional materials, re-emission of absorbed radiation passes from a lower intensity, and for a long time (several hours).
Luminescence of crystals depends on the presence of impurities, the energy levels of which can serve as the levels of absorption, intermediate or radiative levels.
The excitation light, an electric shock or a particle beam create the free electrons, holes and excitons in them. They can be captured by traps which are impurity atoms deposited on the crystal lattice defects. In this case, recombination (and illumination) of electrons and holes don't occur immediately, but after a long time, which would correspond to the duration of phosphorescence.