Contribution ofJmixing to the5D0−7F0transition ofEu3+ions in several host matrices

The ${}_{}{}^5{}_{}{}^{}$ ${\mathit{D}}_{0\mathrm{-}}^7$ ${\mathit{F}}_0$ transition mechanism has been investigated for the ${\mathrm{Eu}}^{3+}$ ion in two kinds of oxide glasses, polyvinyl alcohol film, and ${\mathrm{Y}}_2$ ${\mathrm{O}}_2$S crystal powder, from the analysis of the laser-induced fluorescence spectra. In the case of ${\mathrm{Eu}}^{3+}$ in sodium silicate glass and sodium germanate glass, it has been found that the ${}_{}{}^5{}_{}{}^{}$ ${\mathit{D}}_{0\mathrm{-}}^7$ ${\mathit{F}}_0$ transition probability of the ions site-selected by the laser-light excitation is approximately proportional to the square of the axial second-order crystal-field parameter ${\mathit{B}}_{20}$. The interpretation of this result is that the dominant mechanism of this transition in these two glasses is due to the borrowing of intensity from the ${}_{}{}^5{}_{}{}^{}$ ${\mathit{D}}_{0\mathrm{-}}^7$ ${\mathit{F}}_2$ (${\mathit{M}}_{\mathit{J}}$=0) transition by the J-mixing effect. In the case of polyvinyl alcohol:${\mathrm{Eu}}^{3+}$ and ${\mathrm{Y}}_2$ ${\mathrm{O}}_2$S:${\mathrm{Eu}}^{3+}$, on the other hand, the contribution of this mechanism has been found to be negligible, from the analysis of the intensity ratio between the ${}_{}{}^5{}_{}{}^{}$ ${\mathit{D}}_{0\mathrm{-}}^7$ ${\mathit{F}}_0$ and ${}_{}{}^5{}_{}{}^{}$ ${\mathit{D}}_{0\mathrm{-}}^7$ ${\mathit{F}}_2$ transitions. Furthermore, in the above two kinds of glass samples, the site-to-site variations in the energy of the ${}_{}{}^7{}_{}{}^{}$ ${\mathit{F}}_0$ state and the mean energy of the three ${}_{}{}^7{}_{}{}^{}$ ${\mathit{F}}_1$ Stark levels are explained well by the mixing of the ${}_{}{}^7{}_{}{}^{}$ ${\mathit{F}}_2$ state due to the second-order crystal-field potential. To explain the above energy variations in polyvinyl alcohol:${\mathrm{Eu}}^{3+}$, however, it is necessary, in addition to this effect, to take into account the mixing of the charge-transfer state and/or the J mixing due to the other components of the crystal-field potential.