A fluorescent lamp (or bulb) consists of an evacuated glass tube filled with mercury vapor. A voltage of V is applied across the tube, causing the mercury to ionize and conduct. The mercury gives emission lines at 254 nm and 367 nm. The fluorescent tube is coated with Sr5(PO4)3F (an apatite Eric Weisstein's World of Chemistry analog), with small amounts of rare earth elements Eric Weisstein's World of Chemistry and strontium present as an activator. The activator, through quantum mechanical interactions, allows the mercury and the strontium and rare earth elements Eric Weisstein's World of Chemistry to interact in such a way that an excited Sr* state is possible. The electrons ejected from the excitation of mercury are then absorbed by the impurities, emitting light in the visible portion of the electromagnetic spectrum.
