Exploring Phosphorescence
Glow-in-the-dark materials are used in a wide range of objects. Some such as glow-in-the- dark toothbrushes seem to have little use except a small amount of entertainment; others such as tape used in theater productions provide convenience and safety. To understand how these items emit light begin with some exploration. Start with some phosphorescent objects which are not glowing in the dark. Then, perform a series of experiments to address the following questions:

Does the intensity or color of the light emitted by the object after exposure to light depend on the intensity of the incoming light?

time of exposure to the incoming light?

energy of the incoming light? (Try UV and IR as well as various colors in the visible.)

temperature of the object? (If you can, try very low temperature (dry ice or liquid nitrogen.)

If you have a knowledge of energy bands, create a possible energy band diagram for the phosphorescent materials. Then sketch the electron transitions on your model.