Electron configurations emission spectra

The divalent rare-earth ion Eu has the 4f electronic configuration at the ground states and the 4f 5d electronic configuration at the excited states. The broadband absorption and luminescence of Eu are due to 4f - 4 f 5d transitions. The emission of Eu is very strongly dependent on the host lattice. It can vary from the ultraviolet to the red region of the electromagnetic spectrum. Furthermore, the 4f-5d transition of Eu decays relatively fast, less than a few microseconds [33]. 

If the equilibrium position of the excited state C is located outside the configurational coordinate curve of the ground state, the excited state intersects the ground state in relaxing from B to C, leading to a nonradiative process. As described above, the shape of an optical absorption or emission spectrum is decided by the Franck-Condon factor and also by the electronic population in the vibrational levels at thermal equilibrium. For the special case where both ground and excited states have the same angular frequency, the absorption probability can by calculated with harmonic oscillator wavefunctions in a relatively simple form ... 

The ion Fe has the electronic configuration 3d. It is characterized by extremely strong absorption and is the strongest visible luminescence quencher in minerals, but it has an emission band in the IR part of the spectrum. 

Transition metal ion activators that emit in the visible region of the spectrum belong mainly to the d-3 and d-5 electron configurations, d ions have a characteristic narrow band emission that is largely independent of the crystalline host, d ions are broad band emitters with emission wavelengths that are very sensitive to details of the crystal structure. 

The ground-state electronic configurations (levels) of neutral and singly ionized berkelium were identified as 5f 7s2 (6H15/2) and Sf s1 (7H8), respectively (82). A nuclear magnetic dipole moment of 1.5 nuclear magnetons (61) and a quadrupole moment of 4.7 barns (83) were determined for 249Bk, based on analysis of the hyperfine structure in the berkelium emission spectrum. 

Fig. 2. Splitting of a lanthanide electronic configuration, with (4f ) as an example (1) interelectronic repulsion, (2) spin-orbit coupling, and (3) ligand-field effects. The emission spectrum of Tb(DPA)3 at right is an experimental example of these splittings.

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