Temperature Dependence

Because room temperature energies are sufficient to cause the impurity-to-conduction-band transition, the temperature dependence of phosphorescence is difficult to see. With low temperatures such as liquid nitrogen, you will see it.

 

With the computer program, we can simulate low temperatures. As demonstrated in the program, the toothbrush is dipped in liquid nitrogen that has a temperature of –196°C. The temperature of the toothbrush is about -200 °C when it is brought near the heat lamp. Experiment with the energies until you can explain how the temperature at which an object glows in the dark is related to the energy differences between the conduction and impurity energy bands.