Cathodoluminescence of organo-lanthanide complexes

Abstract

The cathodoluminescence (CL) of organo-lanthanide complexes is studied as a modeling of beta luminescence. It is found that complexes of Sc, La, and lanthanides with anionic ÔO, ÔN bidentate and O-monodentate ligands under excitation by fast electrons display luminescence of various intensities. In the spectra of Sc, La, Nd, Er, and Tm compounds, only broadened bands of the ligands peaked about 450 nm are observed. A similar spectrum gives anthracene, which is used as a reference compound. In contrast, the emission spectra of Eu and Tb compounds contain only the narrow bands of f–f transitions characteristic of these metals. The spectra of Sm, Dy, and Yb derivatives exhibit both the bands of ligands and weak metal-centered luminescence. X-ray luminescence (RL) of several terbium complexes is also investigated. A comparison of the photoluminescence, CL and RL spectra of the studied compounds reveals a similarity of the shape of the spectra but a significant difference in their intensities. Terbium compounds show record scintillating activity. Possible mechanisms of luminescence of organo-lanthanide complexes upon different types of excitation are discussed.