Electron binding energies and how it relates to activator luminescence and bonding in compounds

Methods and models to determine the vacuum referred binding energy (VRBE) of electrons inluminescence impurity states and in host band states are briefly reviewed. Special attention is focussedon how electron bonding within anion ligands of the host compound and bonding betweenluminescence center and those ligands affect VRBEs, electronic properties, and luminescence properties.The chemical shift of 4f-electron VRBE, the centroid shift of 5d-electron VRBE and the Coulomb repulsionenergyUfor Eu appear strongly correlated with bonding and one may predict one from the other. Alsoconduction band and valence band energies of different compounds can be compared with each otherand with reference to the common vacuum energy level. How that provides new insight in luminescenceproperties will be addressed. All models were derived from lanthanide spectroscopy. First results on theVRBE in transition metal impurities with single d-electron states are also reviewed.