Fluorescence Spectrum and Its Intensity of Europium Tris(ethyl sulfate) Enneahydrate

Abstract

Abstract The polarized fluorescence spectrum of the europium tris(ethyl sulfate) enneahydrate crystal was measured at 95 K by using excitation lines of an Ar+ laser. The multipole character of transitions and the energies and crystal quantum numbers for the crystal field components of the 7FJ(J=0, 1,···,6) and 5D0.1 terms were determined from the spectral analysis. It was ascertained that most of the transitions were due to forced electric dipole transitions but some of them due to magnetic dipole transitions, in which nine strong lines appeared as magnetic dipole radiations satisfying the selection rule for ion levels, while three weak lines were magnetic dipole radiations forbidden in ions. The relative intensities of both the forbidden electric dipole transitions and the magnetic dipole transitions were calculated by the crystal field wavefunctions obtained to reproduce the experimental data. From the comparison of the calculated intensities with the observed ones, the ratio of the populations of the 5D0 term to the 5D1 term in fluorescent process was estimated to be about 20, although the 5D0 term was 1750 cm−1 lower than the 5D1 term. The result suggested that the configuration mixing due to g-orbitals was significant to allow electric dipole transitions.