Europium ground state electronic configuration

The ground level electronic configuration of trivalent europium is / . Transitions within the / shell are responsible for the crystal spectra. Transitions are forbidden in a free ion by the parity rule for electric dipole transitions. In a crystal or glass, forced electric transitions become allowed as a consequence of coupling of odd electronic wave functions due to the odd parity terms in the crystal field expansion. Considering the static field approximation in the theory developed by Judd (4) and Ofelt (5), the contribution of the odd parity part of the cr5rstal field is calculated by mixing states of different parity. 

As a relevant example, Figure 6.4 shows the room temperature absorption spectrum of Eu + in sodium chloride (NaCl). In this crystal, europium is incorporated in the divalent state, replacing Na+ lattice ions. The spectrum of Eu + ion in NaCl consists of two broad bands, centered at about 240 nm and 340 nm, which correspond to transitions from the ground state ( 87/2) of the 4f electronic configuration to states of the 4f 5d excited electronic configuration. In fact, the energy separation between... 

The spectrum of singly ionized europium (Eu+, EuII). — The seceond spectrum of europium (Eu II) has been measured by Russell et al. [487]. The ground state is derived from the addition of an electron to the parent core and is found to have the configuration 4/7(8 7/2)6p. They have in particular identified 156 levels originating from to the coupling of a 6s, 6p or 5d electron with the 4/7(8 7/2) core. The lowest terms are 9S and 7S. 

It is difficult to measure a quadrupole splitting in europium compounds because of the electronic configurations of Eu and Eu " ". The Eu ion has a, Af half-filled shell with an electronic ground state of which cannot... 

---