Optical spectroscopy and magnetic studies of dimeric europium capronate with 1,10-phenanthroline

Luminescence, excitation of luminescence and absorption spectra of europium capronate crystals as well as vibrational IR and Raman spectra at 4.2, 77 and 293 K were obtained. Magnetic susceptibility measurements were carried out down to 1.7 K. Correlations between the spectral and magnetic properties and details of the structure of the title compound were studied. The crystal field parameters were calculated using the Stark splitting of the Eu³⁺ electronic levels. The oscillator strengths were evaluated. Changes in the spectra and magnetic susceptibility of Eu(C₅H₁₁COO)₃Phen with increasing temperature from 4.2 to 293 K proves transformation of the crystal lattice. The subtle splitting of bands in the regions of the ⁵D₀→⁷F₁ and ⁵D₀→⁷F₂ transitions was revealed. Several possible causes of this phenomenon, including resonant vibronic interactions and/or the possible effect of ion-pair interactions, are discussed.