Factors Associated with Excitation Energy Conversion

- FACTORS ASSOCIATED WITH EXCITATION ENERGY CONVERSION 

There are two types of ener transfer from a point in a lattice to a luminescent center. For semi-conducting phosphors like ZnS, migration of electrons in the conduction band, or holes in the valence band, conve3rs the excitation energy to localized luminescent centers. Excltons (bound electron-hole pairs) is another mechanism. For insulators (which are generally oxygen dominated compositions), the excitation energy can be transferred from an excited point in the lattice, or from an excited luminescent center to other unexcited centers in the lattice by Quantum Mechanical resonance. 

Resonant energy transfer mechanisms include those given in 5.6.1., presented on the next page. 

Exchange interactions Phonon assisted energy transfer Excitation diffusion Sensitization of luminescence 

We can summarize the material in Section 5.5. as follows. Essentially, we have treated a phosphor as a one-electron process. The sequences for changes in electronic states are  

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Factors associated with excitation energy conversion 419... 

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