luminescence

luminescence (In French luminescence) the ability of solids, liquids or gases to emit light of a certain wavelength spectrum during the transition from a stimulated state to a basic state. The emission of light always requires an internal or external stimulation: through electric current (LEDs, OLEDs), light particles (phosphorescence: afterglow; fluorescence: real-time luminescence), chemical reactions (luminol in forensic medicine, luciferin in glowworms), heat input (embers), X-rays (projection screen), amplification through stimulated emission (laser) etc.