Vibronic Transitions in Centrosymmetric [Eu$\text{}_{x}$La$\text{}_{1-x}$(AP)$\text{}_{6}$](ClO$\text{}_{4}$)$\text{}_{3}$ Crystals

The optical excitation and emission spectra of Eu(III) in [Eu$\text{}_{x}$La$\text{}_{1-x}$(AP)$\text{}_{6}$](ClO$\text{}_{4}$)$\text{}_{3}$ centrosymmetric complex were measured. The vibronic transitions were observed in excitation and emission spectra. Following the vibrational analysis' of the infrared and Raman spectra of [Pr$\text{}_{x}$La$\text{}_{1-x}$(AP)$\text{}_{6}$](ClO$\text{}_{4}$)$\text{}_{3}$, the assignment of [Eu$\text{}_{x}$La$\text{}_{1-x}$(AP)$\text{}_{6}$](ClO$\text{}_{4}$)$\text{}_{3}$ vibronics was given The concentration effect on excitation and emission spectra was investigated. It was found that the vibronic intensities were changed upon the concentration effect. The intensive charge transfer bands were observed in blue region. Their intensities decreased with increasing concentration.