Define the term phosphorescence. Explain characteristics luminescent materials. Explain noncharacteristic luminescent materials. Define photoluminescence. . What is meant by cathodoluminescence? What...

Define the term phosphorescence. Explain characteristics luminescent materials. Explain noncharacteristic luminescent materials. Define photoluminescence. . What is meant by cathodoluminescence? What is meant by electroluminescence? Define thermolumine scence. What is meant by activators? What is meant by coactivators? . Explain how a p-n junction radiates energy.