Analysis of Fluorescence Spectra of Rare-Earth Chelates. II. Dipyridyl Complexes of Europic Chloride

The emission spectra of two dipyridyl complexes of EuCl₃ were analyzed in detail treating the ligand field as a perturbation on the free‐ion levels. The ligand‐field parameters were calculated from the splitting in the ${}^7{F}_1$ and ${}^7{F}_2$ levels of the Eu^3 + ion without assuming a known molecular geometry and the model suggested by these parameters is discussed. In addition, the ligand‐field parameters are used to calculate interatomic distances and to compare the coordinative properties of water and dipyridyl ligands. The method developed for deriving and verifying the geometrical arrangement and interatomic distances from fluorescence spectra proves to be a powerful tool.