Is photoluminescent technology new?
Photoluminescence was studied by the British physicist Sir George Stokes in 1852, who found that the emitted light depended on the chemical composition of the material rather than the spectral range of the excitation source. A few years later in 1859, the French researcher described the first of many photoluminescent materials that absorb ultraviolet radiation and emit visible light. The excited electrons in photoluminescent materials remain in a “metastable” energy state for minutes to weeks. The materials emit light continuously when they are excited by ultraviolet or visible light. When the excitation source is extinguished, the materials continue to emit light, called afterglow that we perceive as “glow-in-the-dark.” Today, photoluminescent materials are used as safety and instrument markings in airplanes, rail, ships, power plants, and by NASA in the space shuttle and the International Space Station.
