Multiplet Structure in the Absorption Spectrum of Eu2+

Abstract

The Eu2+ ion in alkaline earth fluorides produces two broad absorption bands arising from 4f−5d transitions. The band at 3 eV has a structure with six resolved peaks. This structure is independent of Eu concentration. This band is attributed to transitions from the 4f7(8S) ground state to 4f6(7FJ) 5eg, the peaks being associated with the different J values in f6(7F). The higher energy band in the fluorides and the absorption band in the europous chalcognides are correspondingly attributed to 4f6(7FJ) 5t2g states. With this model, with 7FJ intervals obtained from the resolved structure in the EuF2 data, and from the experimental oscillator strengths of the observed absorption bands, the 4f−5d radial integral is calculated and a consistent set of values of 0.23±0.01 Å obtained. The Faraday and Voigt magneto-optic effects are calculated for EuF2 at 4330 Å. The room-temperature Verdet constant is −7.1 min/Oe·cm as compared with the experimental value of −6.6 min/Oe·cm. The Voigt birefringence at 15°K and 20 kOe is n∥−-n⊥=−2.0×10−4 while experiment gives −1.7×10−4.