What is the glow in the dark materials?

Objects in the ultraviolet light, the sun light or ordinary light irradiation, the object has a luminescence properties of some in the dark environment, called the object called photoluminescence materials. Also called the long afterglow luminescent material and luminescent films. Their emission intensity and delay time and the object of the related materials. Light emitting a variety of materials, long to see long phosphorescent phosphor and multi-color long afterglow phosphor. Long phosphorescent phosphor is made of zinc sulfide phosphor and phosphor copper, the cost is low, but because the disadvantages of sulfide unstable, easy deliquescence, anti aging poor, afterglow short time delay etc.. Long afterglow phosphor in rare earth aluminate phosphor base with two valence rare earth europium and dysprosium made of long afterglow phosphor, fluorescent delay of up to twelve hours or more.