ABSTRACT
The 3d transition metal ions utilized in commercial powder phosphors have three electrons or five electrons occupying the outermost 3d electron orbitals of the ions. When the 3d ions are incorporated into liquids or solids, spectroscopic properties are considerably changed from those of gaseous free ions. These changes are explained in terms of crystal field theory, which assumes anions surrounding the metal ion as point electric charges. Electron wavefunctions can be used as the basis of a representative matrix for the symmetry operations, and the eigenvalues of the Hamiltonian can be characterized by the reduced representations. When the electrostatic interaction is taken into consideration as a small perturbation, the lower symmetry levels split from the levels of these electron configurations. The interaction between an oscillating electromagnetic field of light and an electron brings about a transition between different electronic states.
