Emission spectra and local symmetry of theEu3+ion in polymer electrolytes

Abstract

The emission spectra of poli(ethylene oxide) (PEO) and poli(propylene oxide) (PPO) modified by different concentrations of europium bromide, ${\mathrm{PEO}}_{\mathit{n}}$ ${\mathrm{EuBr}}_3$ (n=8,12,16,20,24,28,32,80) and ${\mathrm{PPO}}_{\mathit{n}}$ ${\mathrm{EuBr}}_3$ (n=32,80), were recorded and the observed lines assigned to the intra 4${\mathit{f}}^{\mathit{N}=6\mathrm{}}$ ${}_{}{}^5{}_{}{}^{}$ ${\mathit{D}}_{0,1}$ ${\to }^7$ ${\mathit{F}}_{0–4}$ transitions. The corresponding Stark levels were identified for the ${}_{}{}^7{}_{}{}^{}$ ${\mathit{F}}_{0–4}$ and ${}_{}{}^5{}_{}{}^{}$ ${\mathit{D}}_0$ states. The luminescence of both these polymer complexes (presenting almost identical characteristics) is sufficiently intense to suggest their use as possible luminescence devices. The local coordination of a rare-earth ion in polymer electrolytes is attempted. We used a local-field interaction model, the polarization behavior of the ${}_{}{}^5{}_{}{}^{}$ ${\mathit{D}}_0$ ${\to }^7$ ${\mathit{F}}_0$ transition, certain moment operators, and the allowed optical activity of the ${}_{}{}^7{}_{}{}^{}$ ${\mathit{F}}_{2,3,4}$ components for identifying the approximate local symmetry of ${\mathrm{Eu}}^{3+}$ to the ${\mathrm{C}}_{2\mathit{v}}$ point group.