Energy Processes in a Phosphor

000 cm-i = ultraviolet light) is absorbed by a phosphor, then the phosphor might emit a photon of say 2.48 ev. (5000 A = 20,000 cm-1 = green light). This is a so-called Stokes process where less energy is 

The sequence of energy processes that occur within a phosphor include  

In a phosphor, absorption of energy may occur in the host, or directly in the activator center (the added transition metal ion). But it is the activator center (or site) which becomes excited, whether by transfer of energy from the host, or not. That is, the activator center absorbs the energy and changes its electronic energy state from a ground state to an excited state. 

This is a representation for a single activator center. Herein, we use spectroscopic notation for the ground and lowest energy excited states (We will explain this later). Tlius, the electronic energy (involving a one electron transition) is  

Let us now Interpret the above diagram so that we can understand the electronic processes which occur in a phosphor. 

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Times Associated with Energy Processes in a Phosphor... 

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